Ironic requires pyghmi>=0.5.8

Ironic import pyghmi exceptions, however it is ready in pyghmi>=0.5.8
Enable this in requirement first, then Ironic will use it

Change-Id: I29b70d622f06e4304209dd958e17dc27c437dc7b
Partial-Bug: #1264945
Update oauthlib requirement to at least 0.6

The oauthlib requirement was not limited. A recent change to
Keystone doesn't work with versions of oauthlib < 0.6.

Change-Id: Ied4d1aea8fba28ec739dbbdc2f5a6ea2194d1674
Closes-Bug: #1270909
Merge "Update oauthlib requirement to at least 0.6"
Merge "Ironic requires pyghmi>=0.5.8"