fix(Tutorials): Point back to angular 1.2.26

For some reason in 1.3 ngClass is refusing to change with $scope alerations on
the tutorials but it works fine outside of them. Probably has to do
something with grunt-ngdocs or our custom changes to it.
fix(GridRenderContainer): Redraw with scroll %

Use previous scroll percentage to redraw, not the previous scrollLeft
value. The scrollLeft is too imprecise and is causing large canvases to
redraw out of place. To reproduce, you could scroll the "Horizontal
Scrolling" tutorial all the way right and then sort (or manually call
grid.refresh()). Changing redrawInPlace() to use the previous scroll
percentages fixes the issue.

Fixes #2357
chore(Header/Footer) Remove group-panel elements from header and footer.  Grouping should be in it's own feature module when it is developed
chore(docs) Add a note about gridOptions.footerTemplate
Fix #2343 (selection) header height
Merge pull request #2363 from PaulL1/2343_header_height

Fix #2343 (selection) header height
Fix #2355 (selection) allow width smaller than 30 px
Merge pull request #2367 from PaulL1/2355_selection_width

Fix #2355 (selection) allow width smaller than 30 px
Fix #2356 #1979 (gridMenu): add enableHiding to tutorial
Merge pull request #2368 from PaulL1/2356_column_hiding

Fix #2356 #1979 (gridMenu): add enableHiding to tutorial
Fix #2360 (gridCol): build column only copies sort if new col
Merge pull request #2369 from PaulL1/2356_column_hiding

Fix #2360 (gridCol): build column only copies sort if new col
Fix #2285 (tut, e2e): fixed e2e and extended tut for external sort
Merge pull request #2370 from PaulL1/2285_external_sort

Fix #2285 (tut, e2e): fixed e2e and extended tut for external sort
Fix #2256 (menu): position absolute rather than fixed, fixes safari
Merge pull request #2371 from PaulL1/2256_grid_menu_safari

Fix #2256 (menu): position absolute rather than fixed, fixes safari
Fix #2161 #2120 (cellClass): watch that notices changed cell, update cellClass
Merge pull request #2374 from PaulL1/2161_cell_class

Fix #2161 #2120 (cellClass): watch that notices changed cell, update cel...
Fix #2221 (cellNav): Add scrollToFocus method
Merge pull request #2376 from PaulL1/2221_scrollToFocus

Fix #2221 (cellNav): Add scrollToFocus method