Fix bash-it prompt

* Overriding PROMPT_COMMAND kills the bash it theme system
* So stop doing that
Simplification and changes to be able to install bash-it globally
Allow a custom fork of bash-it

Since the bash-it maintainer isn't very fast in approving theme pull requests, i needed my fork and not the main bash-it repository. So i moved the repo url to the attributes file
This version limitation is more a hassle than a benefit, but this might be personal preference
Update recipes/textmate2.rb

1/3/2013 version of TextMate 2
Re-enable version limitation
updated vim-hash to pull in new location for vim-slim
LWRP for sysctl
increase_shared_memory uses LWRP
Aggressive TCP keepalive/keepidle settings

...to match Pivotal's equally aggressive firewall setttings'
TCP keepalives in default Pivotal configuration