* [API] Add notification endpoints

 * add func GetNotifications(opts FindNotificationOptions)
 * add func (n *Notification) APIFormat()
 * add func (nl NotificationList) APIFormat()
 * add func (n *Notification) APIURL()
 * add func (nl NotificationList) APIFormat()
 * add LoadAttributes functions (loadRepo, loadIssue, loadComment, loadUser)
 * add func (c *Comment) APIURL()
 * add func (issue *Issue) GetLastComment()
 * add endpoint GET /notifications
 * add endpoint PUT /notifications
 * add endpoint GET /repos/{owner}/{repo}/notifications
 * add endpoint PUT /repos/{owner}/{repo}/notifications
 * add endpoint GET /notifications/threads/{id}
 * add endpoint PATCH /notifications/threads/{id}

* Add TEST

* code format

* code format

* Improve notifications

* batch load user

* Update notification only when read

* Fix reorder

* fix lint

* fix test

* fix lint

* make function meaningful

* fix comment

* Add 'mark all read' option to notifications

Signed-off-by: Sasha Varlamov <sasha@sashavarlamov.com>

* Fix exported comment

Signed-off-by: Sasha Varlamov <sasha@sashavarlamov.com>

* Format method comments

Signed-off-by: Sasha Varlamov <sasha@sashavarlamov.com>

* Fix exported comment

Signed-off-by: Sasha Varlamov <sasha@sashavarlamov.com>

Format method comments

Signed-off-by: Sasha Varlamov <sasha@sashavarlamov.com>

Tests for reactions (#3083)

* Unit tests for reactions

* Fix import order

Signed-off-by: Lauris Bukšis-Haberkorns <lauris@nix.lv>

Fix reaction possition when there is attachments (#3099)

Refactor notifications swap function

* Accept change to drop beforeupdate call

* Update purge notifications error message for consistency

* Drop unnecessary check for mark all as read button

* Remove debugging comment

* hide unactive on explore users and some refactors

* fix test for removed Organizations

* fix test for removed Organizations

* fix imports

* fix logic bug

* refactor the toConds

* Rename TestOrganizations to TestSearchUsers and add tests for users

* fix other tests

* fix other tests

* fix watchers tests

* fix comments and remove unused code

* Filter inactive users before sending emails or creating browser notifications

Signed-off-by: David Schneiderbauer <dschneiderbauer@gmail.com>

* fix formatting issues

Signed-off-by: David Schneiderbauer <dschneiderbauer@gmail.com>

* included requested changes

Signed-off-by: David Schneiderbauer <dschneiderbauer@gmail.com>

* optimized database queries

* rebasing new master and add tablenames for clarification in xorm queries

* remove escaped quotationmarks using backticks

Signed-off-by: David Schneiderbauer <dschneiderbauer@gmail.com>

* Fix tests code to prevent some runtime errors

* Reduce nesting

* Unit tests and remove unused functions in models/notification

* Read -> Unread