Update required Fabric version to 1.5.2 [#94]
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.

badele/fabtools,ronnix/fabtools,davidcaste/fabtools,sociateru/fabtools,AMOSoft/fabtools,ahnjungho/fabtools,bitmonk/fabtools,wagigi/fabtools-python,prologic/fabtools,hagai26/fabtools,fabtools/fabtools,pombredanne/fabtools,n0n0x/fabtools-python