Add distro_codename variable to apt repository

Allows one to specify "http://example.com/ubuntu %(distro_codename)s main" as
the APT url.
Add pre start script to Upstart

Similar to post stop, could probably be optimized.
Key:value variants, comparisons

 - Compare installed and requested variants
 - Use them as key:value, not just key anymore
 - Compare values (LooseVersion)
VirtualEnv python_version: default to just 'python'

This way we can always use it as the executable name in other places - maybe
rename it then?
Merge pull request #2 from janfabry/upstart/pre_start

Add pre start script to Upstart
Merge pull request #1 from janfabry/apt_get/distro_codename

Add distro_codename variable to apt repository
Merge pull request #4 from janfabry/virtualenv/python_version

VirtualEnv python_version: default to just 'python'
cd_path added: using --path= as a parameter to ./client.py, you can start at a certain service node. Also removed older, not correctly implemented --run option.
get_width/height added to PTY.
Better prompt. (scroll when the command prompt becomes larger than the terminal width)
1.0.7 release.
bug fix in upstart pre_start_script.
new uwsgi version.
bug fix concerning isolations and parent references from a service containing its own Hosts definitions.
Cleanup isolated AptGet and Redis services

Because they are isolated, we can replace self.hosts with self.host.
AptGet utilities: is_package_available and setup

setup() is used in many other services but not here. Added as a shortcut to
setup the extra sources and install the package.

is_package_available will tell you whether the package is listed in the
installed sources, or whether you will need an extra one.
Variants documentation, private helper methods
map_services and walk_services

map_services might not be the best name for this function, because it is not
a fixed external map function, but a method of the service itself.
Merge pull request #8 from janfabry/utils/map_walk_service

map_services and walk_services
Merge pull request #7 from janfabry/cleanup/hosts

Cleanup isolated AptGet and Redis services