add variables column
refactored language to use new variables column
changed $key to $name
removed not needed join of "cm_languageKey_variable" in paging
check if variable names are multiple defined
move all variables to cm_languageKey and drop table
changed script to be able to run multiple times
Moved mysql client config to the service manager

- Added simple CM_Db_LoadBalancer class for read servers
Moved mysql client config to the service manager

- Code adjustments
Merge branch 'master' of github.com:cargomedia/CM into issue-1195

Conflicts:
	resources/config/default.php
	resources/config/test.php
Merge branch 'master' of github.com:cargomedia/CM into issue-1195

Conflicts:
	resources/config/default.php
	resources/config/test.php
Dropped load balancer

- Renamed service MySql to Db
Formatting
Merge branch 'master' of github.com:cargomedia/CM into issue-1195
Merge branch 'master' of github.com:cargomedia/CM into issue-1195
Renamed DbReadOnly to DbRead
Added service DbMaintenance
Passed CM_Db_Client instance to CM_Db_Db::exec()

- Removed parameter passed to getClient($readOnly)
- Added helper methods getClientRead() and getClientMaintenance()
- Client instances not referenced on CM_Db_Db any more, but on the CM_ServiceManager instance
- Removed _getReadOnlyAvailable() and flag $config->serversReadEnabled for simplicity
- Simplified service configuration
- Adjusted usages
Rationalized usages of CM_Db_Db::getConfigDefault()

- Introduced CM_Db_Db::getClientWithoutDatabase() to cover most usages
- Used directly CM_Db_Db::getClient() in tests
Used same db connexion to quote identifiers and to execute queries

- Only concerns existsColumn() and existsIndex(), used in migration scripts