Front end for scheduling tasks

Add scheduled tasks view
Add scheduled tasks sidebar link in system sidebar
Front end for scheduled tasks

Add views and template to create a scheduled task
Modified icon for scheduled tasks
Front end for scheduling tasks

Add tooltips for add task page
Merge branch 'issue#219_schedule_tasks' of git://github.com/sujeetsr/rockstor-core into sujeetsr-issue#219_schedule_tasks
Update task models for scheduling tasks. Separate task definition, task and
task_type into separate models.
Update task schedule api to exclusively deal with task/event definitions.
clean up deprecated code in replication and sprobes.
Implement task log view for listing history of a recurring task def.
Implement a simple view for task types.
Add enable/disable support to events.
Update task handling cli according to new backend changes.
Disable create pool button when no disks exist.
Merge branch 'issue#225_createpool_disable' of git://github.com/Mchakravartula/rockstor-core into Mchakravartula-issue#225_createpool_disable
Disable create button when no disks available.
Merge branch 'issue#225_createpool_disable' of git://github.com/Mchakravartula/rockstor-core into Mchakravartula-issue#225_createpool_disable
Merge branch 'master' into issue#219_schedule_tasks

Conflicts:
	src/rockstor/smart_manager/models/task_def.py

Display scheduled tasks
Add datepicker and timepicker to add task form
Change cosmetics of the disable button and tool tip information.
Merge branch 'master' of github.com:schakrava/rockstor-core
Front end for scheduled tasks

Use inline fields in add task form
Load task log
Rename models to taskdef and task