comments: cosmetic changes

* The comments' text area is now larger;
* Included 'add comment' form popover which explains how to add notes;
* Added a warning when viewing the notes, informing the user that this is a
summarized view of the whole record discussion;
* Replies to original comments can be sent directly from the notes page;
* Radio buttons to switch between comments and notes;
* Notes feature flag.

Signed-off-by: Adrian-Tudor Panescu <adrian.tudor.panescu@cern.ch>
comments: hierarchic notes improvements

* Notes are ordered by creation date (fuzzy);
* Notes are now displayed hierarchically (Note on Page 1, Figure 2);
* Spelling corrections;
* Collapsible notes UI support;
* CSS/ JS in base.html moved to static;
* Disabled collapse href in order to avoid redirections (comments/ notes);
* Refactoring and cleanup.

Signed-off-by: Adrian-Tudor Panescu <adrian.tudor.panescu@cern.ch>
unit tests

* Updated note unit tests and fixed some minor found bugs;
* Fixed issue with notes/ comments selected option not being correctly displayed
in UI when no comments existed;
* utils.washers unit tests

Signed-off-by: Adrian-Tudor Panescu <adrian.tudor.panescu@cern.ch>