Make the SSH authentication methods used by the server configurable,
so that for example password authentication can be turned off.

For this, a `git.sshAuthenticationMethods` setting is added which is a space
separated list of authentication method names. Only the methods listed will
be enabled in the server.
This is modeled after the option of the same name from sshd_config, but it
does not offer listing multiple required methods. It leaves the door open,
though, for a later extension to support such a multi-factor authentication.

Since this also includes Kerberos authentication with GSS API, this obsoletes
the `git.sshWithKrb5` property. The latter is removed. Instead, to enable
Kerberos5 authentication, add the method name `gssapi-with-mic` to the
authentication methods list.

+ Multiple commits in a single push

+ Supports referencing:
  + Tickets from other tickets via comments
  + Tickets from commits on any branch
+ Common TicketLink class used for both commits and tickets
  + TicketLink is temporary and persisted to ticket as a Reference
+ Support deletion of ticket references
  + Rebasing patchsets/branches will generate new references
  + Deleting old patchsets/branches will remove the relevant references
+ Substantial testing of use cases
  + With and without patchsets, deleting, amending
  + BranchTicketService used during testing to allow end-to-end ref testing
+ Relocated common git helper functions to JGitUtils

+ Prevent Edit of old doc version

+ New docEdit page with links from docPage and docList
+ Bespoke menu system with full screen edit mode
+ npm required for building client side scripts
+ Ant script added for BuildUI which performs npm commands
+ Update font-awesome to 4.5.0
+ Factor out to JGitUtils common code in BranchTicketService for EditFilePage
	+ getTreeEntries
	+ commitIndex
+ Merge capability for document editing

+ View and Raw both download the actual file
+ Blame will show the metafile

Replaced the canAccess() method in RpcFilter with !adminRequest,
that should solve the problem.

When calling a servlet which has already been authenticated, the server would produce
a lot of superfluous log entries, e.g:

Called servlet authenticate when request is already authenticated.

The log level for this log entry has been lowered down to DEBUG.

The AuthenticationManager did not encounter for FEDERATION_USER and would unnecessarily
generate a lot of failure warning log messages, e.g:

Failed login attempt for $gitblit, invalid credentials from XXX.XX.XX.XX

A simple condition will prematurely return null bypassing the regular authentication path
and immediately make the authentication be routed via FederationManager.

+ GitLFS client support
+ FilestoreModel now parses meta file
+ Read meta heading from cache if available
+ Authentication based on accept headers for browser view filestore login
+ PathModel & PathChangeModel now understands filestore items
+ Zip & Rar downloads contain include filestore items
+ Filestore servlet returns LFS JSON error only if accepted by client
+ DiffStat now knows repository to allow identification of filestore items
+ Filestore items identified and returned via view, raw & blob links on
blame, commitDiff, commit and Tree pages

groovy.jenkinsGitbaseurl in gitblit.properties or web.xml can
override the http default protocol

+ JS patch/hack to coerce legacy wicket into talking to a HTML5 input type
+ JS script to hide inline help on date format when using HTML5 date picker
  + Date picker shown in user locale and standard does not support custom
  format.
  + Always sent in ISO8601 format

This was unused and causing provider lookup to fail in
AuthenticationManager.findProvider() by changing it out
from underneath. As a result, the supportXChanges methods
weren't being reported correctly.

+ Filestore listing filtered by user view permissions
+ Configuration help for filestore relocated to website files
+ Added migration example

+ Allows using lfs when `server.contextPath = /git`

This was originally from https://github.com/gitblit/gitblit/pull/950 but seems to have been reverted when develop branch was merged with master.