Handle 404 and 500 errors

Use custom handler for 404 and 500 errors
Redirect to #404 and #500 so that pages are rendered correctly,
and backbone can display appropriate error templates
Merge branch 'master' into issue#345_404
Merge branch 'issue#345_404' of git://github.com/sujeetsr/rockstor-core into sujeetsr-issue#345_404
Modified template and html files
Merge branch 'issue#345_404' of git://github.com/sujeetsr/rockstor-core into sujeetsr-issue#345_404
Add 404 and 500 views to views/__init__
Merge branch 'issue#345_404' of git://github.com/sujeetsr/rockstor-core into sujeetsr-issue#345_404
Added 404 and 500 views
Merge branch 'issue#345_404' of git://github.com/sujeetsr/rockstor-core into sujeetsr-issue#345_404
Fixes issue #346.

In smart manager sink, django orm is used to write to sqlite3 in
autocommit(default) which causes database locking issues when there's a
constant stream of updates in the sink. Use commit_on_success and batch writes
to mitigate this issue.
Handle 404 and 500 errors

Add global error handler for ajax error
Add global error message template
Remove cutom 404 adn 500 django handler view
Modify 404.html and 500.html
Fixes #348

Update smart probe kernel modules for 2.0
Dashboard widget query modifications

Change t1 to be the timestamp of the last data point from the previous
dataset, instead of previous t2
Remove commented code
Merge pull request #352 from schakrava/issue#346_database_locked

Fixes  #346.
Update t1 from data only if data is not empty
CPU Widget data updates

Update current dataset independently of graph.
Update current window independent of dataset
Create a base buildout with the common parts for all environments.
Merge branch 'issue#356_no_data_widget' of git://github.com/sujeetsr/rockstor-core into sujeetsr-issue#356_no_data_widget
Change journal mode to WAL in db templates