cleaning, unused files
add way to get attachment frontend url from attachments service
wip
Comments read endpoints, some improvements to diagrams widget
add comment create/update and oauth login/authorize
add way to get params from request, add ladybug for templators
delete comment acction, some code style fixes, typos
add cors stuff
Merge pull request #522 from ahilles107/comments_api

This PR was merged into sourcefabric:master branch.

Discussion
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Comments API + attachments updates

                      
| Q             | A    |
| ------------- | ------------- |
| Bug Fix?:     | n    |
| New Feature?: | y    |
| BC Breaks?:   | n    |
| Deprecations?: | n    |
| Tests Pass?:  | y    |
| License:      | GPL-3 | 

Comments REST API
* [x] GET /comments # for all
* [x] GET /comments/{commentid} # single comment
* [x] GET /comments/article/{articleid}/{languageid}/ # for all
* [x] GET /comments/article/{articleid}/{languageid}/recommended # for recommended
* [x] POST /comments/article/{articleid}/{languageid}/ # insert new comment
* [x] PATCH /comments/{commentid}
* [x] PATCH /comments/article/{articleid}/{languageid}/{commentid}
* [x] DELETE /comments/{commentid}
* [x] DELETE /comments/article/{articleid}/{languageid}/{commentid}

Provide REST API for Comments resource + fix some attchments stuff

Commits
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dcd7585579f1c2f5a7d74ff246f46b97b862a62d cleaning, unused files ahilles107
58342979ee1d0b836a913ca85b4467aab7a7a794 add way to get attachment frontend url from attachments service ahilles107
4340f92120af61ecd08df1644ab30b067b3bbffd wip ahilles107
3cd52526fa5726941dcc8f50c35708f26b65ce54 Comments read endpoints, some improvements to diagrams widget ahilles107
8b10cbd826f35d2e4d73ef3d2f73c00f603a2fc2 add comment create/update and oauth login/authorize ahilles107
72e10c52fc35ee7a5ac52e3cd7077778608329a3 add way to get params from request, add ladybug for templators ahilles107
c71fb34839d9945e927cd7e37482385625776429 delete comment acction, some code style fixes, typos ahilles107
5d2a79ba91c9922d78b37b9932b908145fbb6c5b add cors stuff ahilles107