Added test_vm_discovery.py

1. Added cfme/tests/infrastructure/test_vm_discovery.py
Tests whether cfme will discover a vm change (add/delete) without being manually refreshed

2. Implemented version.pick() for the name of the 'Archive' tree element in the navigation menu (using updated key for downstream)
Merge pull request #847 from slouderm/test_vm_discovery

Test vm discovery
fixed flake errors
Merge pull request #953 from slouderm/test_vm_discovery

fixed flake errors
Migrate server_roles fixture from old to new code
Merge pull request #936 from jkrocil/fixture-server-role-migrate

Migrate server_roles fixture from old to new code
Bugzilla update:

* Do not fail if the test item does not have callspec.
* Check only bugs that are in the final collection (save time)
Merge pull request #954 from mfalesni/bz-update

Bugzilla update
test_docs porting to new codebase.
Merge pull request #861 from mfalesni/test_docs

Rewrite docs tests into new code