New Feature: Make minion enabled by default.

We use minion for db updates, modules install/unstall upgrade and
backgorund jobs in future. So make it available all the time.
Update feature: Initial support of Migrations in Module install/uninstall
New feature: Now modules can be loaded from anywhere.

Modules can be on anywhere in the system and paths can be configured
in site config and will be loaded and controlled from admin/modules
One can even hide the module to be displayed on list by adding
visible = 0 in module.info file.
Fixed issue: Fixed schema in previous commit
Fixed issue: Admin layout fixes and minor changes
Fixed issue: Admin module layout cleanup
Fixed issue: Some design icons and tabledrag fixes.
Fixed issue: Minor cleanup
New feature: Allow custom theme paths and better theme handling
Fix issue: Caching only in production
Fix issue: Caching only in production
Fixed issue #688 : This fixes the partial issue. @sergeyklay
New Feature: Initial Datapicker widget. WIP
Fixed issue: Fixed issue in previous commit
New feature: Added initial messages for validation PM
New feature: Added initial Validation_Message
Updated feature: Now messages can be sent or saved
Fixed feature: Changed method name visibility

// @sandeep
+ May be Validation_Message::exists should be moved to
User::exists class?
+ May be should use User::lookup_by_name instead
Validation_Message::exists?
Fixed issue: Cleanup indents
Fixed issue: Improved rule