Disable redundant DB initialization on guesagent's start

Reasons:
 - Guestagent uses conductor to communicate with database.
 - No direct connection to DB is required.
   But GA still initializes DB connection on start.
   This prevent running guestagent without MySQL installed in guest,
   which could be useful for datastores other then MySQL.

Changes:
 - This patch disables DB initialization on GA start.

Closes-bug: #1256046
Change-Id: I23dafdfbc7b04c24f1b4ddd714005eb615641cd6
Replaces local generate_uuid with common.utils

Reasons:
- generate_uuid is defined locally to use truncated uuid,
  without any specific need.
- This may result in similar UUIDs.
- Since tests work fine with usual common.utils.generate_uuid.

Reasons:
- Replaces local generate_uuid with generate_uuid from common.utils.

Change-Id: I5d46ba78169ce26c18c05160f02a8b01f88aca40
Closes-Bug: #1272685
Fix Occasional test_one_network_label_exact Fail

fixes the occasional tox failure for test_one_network_label_exact by
saving and restoring the original conf values before every test.

see bug details for more information.

Closes-Bug: #1272806

Change-Id: Ib051b5325c0914f2ab3bc293b0052abe8257996d
Makes the backup tests less onerous

The backups test code was looking for an exact number of elements to
be returned from the backups list calls. This made running the tests
kind of a pain, so this commit counts the number of backups before a
backup is created and uses this for the later assertions.

Change-Id: I186c9e04a91e86fca612078415413468757297ca
Simplify swift storage load logic

* Use the swift connect to download files.
* Consolidate fake swift objects.

Closes-Bug: #1253752

Change-Id: Ieb1ec1c468e863109e71fe5a0277834cbc692169
Fix default_datastore migration script

Fixes the migration script introduced earlier to remove
dependencies on the Trove database model classes.

Change-Id: I71762baa095039f65e97b3413a7ff0fc3e0014ec
Closes-Bug: 1259642
Merge "Fix Occasional test_one_network_label_exact Fail"
Merge "Makes the backup tests less onerous"
Merge "Simplify swift storage load logic"
Merge "Disable redundant DB initialization on guesagent's start"
Merge "Fix default_datastore migration script"
Merge "Replaces local generate_uuid with common.utils"