Access to heat API via python-heatclient

This adds python-heatclient as a dependency and a simple function
to get a client reference.

Required for blueprint: heat-ui

Change-Id: I5f7d8c7c17f6e78d3f88cc39d50826416b48ad2c
Preparing for Heat tests

Required for blueprint: heat-ui

Change-Id: Ibac4ab7d238ab946a096767218faf9e222699cb6
Merge "Access to heat API via python-heatclient"
Merge "Preparing for Heat tests"