Remove un-needed segment in the route.
Add option to filter databases and collections.
Styling changes to accomodate new search box.
Fix a bug in the updation of selectedItem.
Fix to remove stale references to `content`.

There was a bug in the filtering logic which would lead to stale
references to old `content` being retained on the `originalContent`
field of the filterableContentMixin. This commit fixes the issue by
explicitly forcing the route to call initialize on the mixin.
TODO: Kill this hack and refactor this on the ember_refactor PR that is
pending.
Update header.handlebars
Update README.md
Start using simpletable for databases' table.
Use Simpletable to display collections listing.