db tweaks

- sessions autocommit
- ping_connection guards against connection timeouts
- adjusted session usage to use db.transaction when writing
Automate Explorer instance tests, fix exists()
Placement Policy for RHEV VMs.

Conflicts:
	utils/mgmt_system.py
Check for placement policy affinity

(cherry picked from commit b6e3bbe8920cace995e67abfc023dd1ccc6ecce6)
ISO Model and Base CRUD test
Merge pull request #651 from seandst/db-module-is-less-terrible

db tweaks
Check if key exists in kwargs.

(cherry picked from commit a3562677676fa9ab24df6014432a24876ba8ad8c)
Downloading reports.
Automated Service Dialog
Merge pull request #644 from sshveta/servicedialog2

Automate Service Dialog
Fix 'not all arguments converted during string formatting' TypeError
typo causing KeyErro when accesing to DB
Merge pull request #676 from mfalesni/jenkins_fixes

Jenkins fixes
Update config/configuration to use URL from currently open browser window for navigation
Fix sel.VALUE => sel.ByValue
Fix utils/appliance
Add utils.db.database_on_server() context manager

Remove db_query decorator
Modifications for the Control model to work on new builds.
Moved appliance tests to cfme/ subdir, modified style of it + style of utils/tests/, removed Unittestzero
Add appliance update test