Move iso8601 dependency from test- to pip-requires

Fixes bug 1097860.

Change-Id: Idcf880f9dfa956e6d240357150a9f5a24372f97a
Use os.path to find ~/keystone-signing (bug 1078947)

Change-Id: Ie816d34299c92ba7d5cf6acf717ccfbf029f724f
Merge "Move iso8601 dependency from test- to pip-requires"