Add Samba exports as top level item in Storage

Add django url and view for listing all samba shares
Add js views and templates for listing all samba shares, and adding a
new samba export
Add delete samba export functionality
Merge branch 'issue#324_samba' of git://github.com/sujeetsr/rockstor-core into sujeetsr-issue#324_samba
In add samba export form, do not show shares that are currently exported
Add cancel handler, make multiple shares selectable
Merge branch 'master' into sujeetsr-issue#324_samba

Conflicts:
	src/rockstor/storageadmin/views/__init__.py
	src/rockstor/templates/storageadmin/js/js/router.js
	src/rockstor/templates/storageadmin/js/js/templates/common/sidenav_storage.jst
	src/rockstor/urls.py
Merge branch 'issue#324_samba' of git://github.com/sujeetsr/rockstor-core into sujeetsr-issue#324_samba
Samba export

Change url for samba export
Add submenu for file sharing in sidenav
Disable add samba export button if no shares available
Filter shares that already are exported through Samba
Update samba model to add share as a one-one field.
Implement Samba API at the top level for operations over multiple shares
Remove exess logging from sftp api
validate that at least one share is selected