[IMP] Store CSRF token in session

generated when needed, reset when user changes
[IMP] Require CSRF token for JSON-RPC calls
[IMP] CSRF token in cookie-based API requests
[DOC] Document cookieauth changes
[IMP] Add config option for CSRF checks
[IMP] Add optional referer check for POST

fixes #1238
[FIX] Check if there is content_length in headers
[FIX] 'Go Back' link pointing to Timetable view now

- Closes #975.
[IMP] New design of contribution navigation bar

* Added icons witch links pointing to timetable and conference list
* Change all <table> tags to <div>
* Closes #975
[FIX] Abstracts - disabled fields

 * Should not be taken into account when checking if they're mandatory;
[FIX] Restore 'go back' in navigation bar
[FIX] Missing CSRF checks
[IMP] OrderedDict available in Python 2.6

 * using `ordereddict` library;
[FIX] Display of public rooms

  * See #1170
Merge branch 'v1.0'
[FIX] Additional tag removal operation
[FIX] Exception caused by groups in submitters

 * Code not prepared to handle groups;
[IMP] CSS header improvements
[IMP] Chairpersons submission rights

* Change 'add chairperson' widget for conferences, meeting and lectures
* Submitters added to AccessController class
* Add possibility to manage materials through event (conference,
* meeting, lecture) main page
[IMP] Add email pending queue for event submitters