[TASK] Remove redundant system extensions

Change-Id: I3129b15590ddb3bedc7125cb5bdf1eb38a48b304

Conflicts: Pretty much every file in all removed extensions...
[TASK] Remove redundant hooks

Change-Id: I73a625b71fa0cd9e242017f65d2157e8ec54cfd8
[TASK] Get completely rid of all ext_typoscript_setup.txt files

Replaced with static TS where this applies - and sane default values where it could not be solved with includable files.

Change-Id: Ia2b2e9227136a0a2c84cc3d6082ec723aa1f5103
[DOC] Add Ocelot-specific information to README file

Change-Id: Ic2d35f198c802ad77c72452bd50f1415851496de
[TASK] Restyle backend login page

Change-Id: Ibcf9f3ac74d199819ee4e831e3acd4b90eec1357