Combining the indexer api and repository api into archiva-repository-api
They have bidirectional dependencies so they are put together in one module.

Adding new classes for a generalized indexer api that will be used for interfaces
and implementation independent tasks.

[MRM-1964] Step to move all indexing features behind archiva API

These issues were found by SLF4J Helper for NetBeans IDE:
http://plugins.netbeans.org/plugin/72557/

As suggested in the SLF4J FAQ:
https://www.slf4j.org/faq.html#logging_performance
.. parameterized logging can improve the efficiency of logger calls when
logging at the specified level is disabled.

In addition, per the FAQ: https://www.slf4j.org/faq.html#paramException
since SLF4J 1.6.0 it is possible to use parameterized logging and also
log an exception/throwable.

toString() is called automatically:
https://www.slf4j.org/faq.html#string_contents

These changes were suggested by SLF4J Helper for NetBeans IDE:
http://plugins.netbeans.org/plugin/72557/

Adding new API module (metadata-statistics-api) for statistics and move the
jcr specific tasks to the metadata store module.

Providing interfaces for the statistics API.

Removing dependencies to store specific libraries (like JCR) from the statistic
modules.

Make use of webapp application URL setting when constructing the HTTP
Location header within redirect responses, which allows clients to
follow them when Archiva runs behind HTTP reverse proxies.

by placing these in the metadata model / API they can be used more broadly,
while the storage-dependant implementation can be in a plugin. This means the
plugins can be removed from the admin implementation, which can then be used
(as required) in the CLI