Remove Component class

Discussion has moved on from implementing components as
top-level template elements, so this can be deleted now.

Change-Id: I8f1b78b8def73da7fb31b7725795f314f962e8b2
Make heat depend on python-heatclient

This will be required soon for one or more of the
following reasons:
* Multi-region invoking stacks on other heat endpoints
* A variant of nested stack which goes through API instead of
  internally
* Orchestrating new heat-based resources (autoscaling, software config)
* Possibly sharing some template parsing and validation between
  client and server by moving this code to client

Change-Id: Ia3e55d1b3bb19e713e4c1ecc341805f3a208844e
Doc usage enhancement

Enable doctest, correct depenencies section, adjust help and build
section.

Change-Id: I6c2f89d64926ee8e32b86299356700446903888b
Merge "Remove Component class"
Merge "Make heat depend on python-heatclient"
Merge "Doc usage enhancement"