Dashboard modifications

Change gutter and padding width for shapeshift plugin
Change sizes of default widgets
Dashboard widget modifications

Modify style of widget header
Set widget sizes (normal and maximized) in definitions in widget views
Modify shapeshift colspan and rowspan to be multiples of 50px with
padding and gutter 5px
Only save widget name, position and maximized status while saving
dashboard configuration
Fix bugs in resize and remove methods
Initialize and save maximimized status of widget correctly.
Dashboard modifications

Set widget-header as drag handle, so widgets can be dragged only by
their header sections.
Dashboard modifications

Change background color of widget to white from transparent, so that it
does not show the widget it is being dragged over.
Set move cursor for widget header, to indicate that it is draggable.
Addresses #263

Update the model to support snapshot visibility toggling
Addresses #263

Update lowlevel snapshotting code to save them in the right location
Addresses #263

Update low level nfs export manipulation code for snapshot visibility.
Fixes #263

Update nfs and snapshot views to support snapshot visibility
Set maxcpus to 8
Merge branch 'issue#263' of https://github.com/schakrava/rockstor-core into schakrava-issue#263
Snapshots

Add visible flag to input form
Show errors using validator if json error msg is returned while creating
a snapshot
Remove deprecated share_detail.js file
Store export directory for the nfs export instead of share mount point in
export mount attribute.
Update replication code as required by other changes of #263
Fixes #261

When smart manager starts, do the necessary mounting and nfs exporting.
Dashboard changes

Modify network util widget to show additional content on maximize
Set initial data to empty array.
Dashboard changes

Modify memory util widget font size to fit in widget
Remove code from disk util widget since it needs to be redone
Return successful response for bootstrap when there are no exports.
Merge pull request #267 from sujeetsr/issue#110_dashboard_cpu

Issue#110 dashboard cpu