[DOC] Updated hands-on for meetings and conferences
[FIX] Download material package list fix

* fixed contribution scheduled on date filter
* fixed session filter
* material types genearation based on event
[FIX] Apply PEP8 on ConferencePacker class

* closes #1156
[FIX] Moved material list rendering to tpl

 * see #1156
[FIX] Shift is pressed tip in TT display event

* check if management mode is enable
* closes #1162
[VER] Updated download URL
[VER] Uploaded GPL version in setup.py
[FIX] Contribution deleted crash video indexes

- Closes #1167
[FIX] HTTP API - No occurrences for empty days
[FIX] Buggy "Linked to" display
[FIX] Refactored method
[FIX] Check protection when access RB from event

* Closes #1171
[FIX] Fix submit protected material
[IMP] Added downlaod file feature through HTTP API
[IMP] Added docs for file download HTTP API

- add file.py common for RH and HTTP API
- closes #1018
[FIX] Small HTTPfile API fixes

* small changes in url params
* changed time name from 'file' to 'bin'
* fixed and updated docs
* closes #1018
[IMP] Moved file download code to `file.py`

 * Better feature separation;
 * Simplified a bit file download code;
 * See #1018;
[IMP] Refactored HTTP API serialization mechanism

 * In order to allow greater flexibility in output formats;
 * Serializers can now set HTTP header parameters;
 * Moved serializers to HTTP API, since they are becoming too HTTP-specific;
 * Allowed HTTP API Hooks to disable caching on demand;
 * see #1018
[FIX] Remove 'move contribution' option from tools

* Closes #1169
[IMP] Trigger email when new manager in category

- Closes #457.