* Add Attachment API
* repos/:owner/:repo/releases (add attachments)
* repos/:owner/:repo/releases/:id (add attachments)
* repos/:owner/:repo/releases/:id/attachments
* repos/:owner/:repo/releases/:id/attachments/:attachment_id

Signed-off-by: Jonas Franz <info@jonasfranz.de>

* Add unit tests for new attachment functions
Fix comments

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* fix lint

* Update vendor.json

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* remove version of sdk

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Fix unit tests
Add missing license header

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Add CreateReleaseAttachment
Add EditReleaseAttachment
Add DeleteReleaseAttachment

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Add filename query parameter for choosing another name for an attachment

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Fix order of imports

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Restricting updatable attachment columns

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* gofmt

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Update go-sdk
Replace Attachments with Assets

Signed-off-by: Jonas Franz <info@jonasfranz.de>

* Update go-sdk

Signed-off-by: Jonas Franz <info@jonasfranz.de>

* Updating go-sdk and regenerating swagger

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Add missing file of go-sdk

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Change origin of code.gitea.io/sdk to code.gitea.io/sdk
Update code.gitea.io/sdk

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Update swagger

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Update updateAttachment

* Use standard lessc and minify CSS using Node.js

This changes the previous nonstandard `lessc` to the official one and
enables CSS minification via the clean-css module.

To build CSS, Node.js is required along with a `npm install` to get the
tools installed locally in node_modules so there is no dependency on
binaries in PATH. Benefits include:

- Allows one to have a standard lessc in PATH.
- Can now use command line switches on lessc.
- Minified CSS brings faster page load times and also has the benefit
  of discouraging contributors from editing CSS directly.

To build CSS, Node.js is required along with a `npm install` to get the
tools installed locally based on the information in `package.json`.

The 'make stylesheet' task was modified to run without condition. This
makes it easier to work on the make task itself without having to delete
files.

Also fixes: https://github.com/go-gitea/gitea/issues/2198

* install node, npm and modules on drone

* .PHONY

* use 'minify' to minify CSS