Skill model change

Skill Model change to import dependencies between skills.
Add Skillplan list page

and add skillplan link in link bar.
Removed all skillplan parts in account.
Added migration for skillplan model
Removed unused import
Add export icon, create new "clear" plan and edit page
new routes for skillplans
some new css for skillplans

- skillplan list btn column size (export, view/edit, delete, edit info)
- skill list in view skillplan page : default cursor is pointer
Some design for skill list.
Merge remote-tracking branch 'upstream/develop' into develop
added skillplan "config" (char, implants, remap)

and some js events / css
Merge remote-tracking branch 'upstream/develop' into develop
added button to plan skill at a specific level.

Changed popover behavior :
- click open
- reclick close
- click on another (while one is open) open the new, close the other.
(default behavior : never close until reclick).

This change has been made to allow the use of buttons (for skill
planning) in the popover
change for new prerequisite (django 1.5 ...)
Merge remote-tracking branch 'upstream/develop' into develop
Add skillplan link
Add jQuery Cookie plugin for ajax requests (to use csrf)
Add the function that add a skill into a plan in ajax

Only does basic stuff for the moment.
Add capitalize filter to error message

forgot to add it
Ajax call to call the python function that add a skill into a plan

unfinished yet.
fix errors in Postgres when using rename_column function