Fix api documentation for scrollbars.

Accessing uiGridConstants scrollbars is possible via uiGridConstants.scrollbars.(ALWAYS|NEVER|WHEN_NEEDED), not uiGridConstants.scrollbar.(...)
#2014
#1815 fixing move column issue in firefox
Merge pull request #2031 from jpuri/master

Fix for issues #2014 and partially #1815
Merge pull request #2028 from mamrehn/patch-1

Fix api documentation for scrollbars.
feat(Interpolation): Handle custom symbols

* Add a postProcessTemplate() function to the gridUtil service that swaps
out interpolation symbols if they're different from the default ones.
* Change getTemplate() to use this function when returning templates
* Add tests to the gridUtil spec for getTemplate() with custom
interpolation symbols

Fixes #1576
fix(uiGridRenderContainer): Inherit position

Change position: relative to position: inherit. This will prevent the
footer from overlapping the viewport content incorrectly.  It appears to
not break anything else that's not currently broken...

Fixes #2030