[TYPO3-caretaker] EXT caretaker_server requirements suggestions

[Georg Kuehnberger]

Ahoi Martin et al,

I had a short review of the manual & the latest SVN commits, and like to 
suggest the below two additions.
regards Georg
PS: In case I should have used the bugtracker @ fore, pls. let me know.

a) you might want to add: css_styled_content and caretaker_instance as 
dependencies (or suggests) in ext_emconf.php of caretaker_server.
- caretaker_instance for the caretaker-server key-generation (needed)
- css_styled_content for FE-Display (optionaly)

b) you might wanna add the php-module requirements (like SSL)
- eighther during installation (how?) or first execution of the 
caretaker_server backend-module (by testing of php-function existance),
- and for sure pls. add it to the documentation.