try to get buttons work
Fix arrow-buttons moving left/right cells into base.
Don't obliterate all notebooks. Only process notebooks with nbdiff metadata.
Add logging statements.
change collumn to be column (spelling)
Hide buttons for cells that can't be merged, like 'empty' and 'unchanged'.
Clicking the merge button replaces the base cell.
Adding TODOs
Add extension js file to gruntfile and fix jshint errors.
Fixed extension to display diffUI only if the metadata is present.
Fixed 1second flash between the hide of the notebook-container.
Added functions to save the base to .ipynb.
Requires the remove_metadata to be defined to remove metadata.
Delete custom.css
Merge pull request #54 from Shurouq/clickable_buttons

Make buttons move chosen cell into "base" column