Upgrade default pip version to 1.3.1
Add support for Vagrant 1.1 providers in functional tests
Add `fabtools.system.cpus` to get the host's CPU count
Less verbose output
Move OS detection functions to `fabtools.system`
Better support for Red Hat based systems
Improve examples in MySQL documentation [#92]
Fix home dir default behaviour in require.user
Update required Fabric version to 1.5.2 [#94]

We now use the `shell_env` context manager, which was introduced
in 1.5.0, but was missing from `fabric.api` until 1.5.2.

This should fix documentation build issues on Read the Docs.
Merge branch 'master' of github.com:ronnix/fabtools

Conflicts:
	fabtools/require/python.py
	fabtools/system.py