Enable deleting multiple stacks with single call

Now "heat stack-delete" can only delete one stack in one request,
this patch enhances this command to allow deletion of multiple
stacks with single call.

Change-Id: Id48bfdbbcd565435725c8a4adf1196dcbb93f9df
Closes-Bug: #1256971
Remove vim header

Vim settings can be done in your vimrc file, there is no need to add
them in each source files. Also if set incorrectly, gate (pep8 check)
will catch your mistakes.

NOTE: openstack.common files are left untouched because they should be
fixed in oslo.

Change-Id: I96fe6479e64a13766e7a974727405423a66cd496
Closes-Bug: #1229324
Added API reference document

The API reference document is missing so addded it and enabled pep8
check for conf.py.

Change-Id: I04236c5427d7ac624781fbfc920a79f855d8cd75
Remove ununsed httplib2 requirement

This is not needed anymore since the logging is handled by
six.moves/httplib.

Change-Id: I4315860648258fb760ea22ca09d0083d7c9afb6c
Closes-Bug: #1266584
Merge "Added API reference document"
Merge "Remove vim header"
Merge "Enable deleting multiple stacks with single call"
Merge "Remove ununsed httplib2 requirement"