Add routes for repository tag editing.

This is to fix the following error:

Error caught: [ActionController::RoutingError] No route matches
{:action=>"tagging_edit",
 :id=>nil,
 :db=>Repository(...),
 :escape=>false,
 :controller=>"repository"}

http://bugzilla.redhat.com/show_bug.cgi?id=1138120
Add missing route and a spec fix

http://bugzilla.redhat.com/show_bug.cgi?id=1138120
Don't sort non-sortable columns

Non-sortable columns, such as row_button, would have grid_obj
set to an empty string.

https://bugzilla.redhat.com/show_bug.cgi?id=1132536
Merge pull request #510 from mzazrivec/fix_repo_tag_routes

Add routes for repository tag editing.
Merge pull request #531 from mzazrivec/button_columns_nosort

Don't sort non-sortable columns
Missing Virtualization Type column for Amazon Images

https://bugzilla.redhat.com/show_bug.cgi?id=1139835

The UI was not displaying the Virtualization Type for
Amazon Images.
Merge pull request #548 from mkanoor/missing_textual_summary

Missing Virtualization Type column for Amazon Images
Add XFS Filesystem Support

- The following portions of the XFS code have been (at least partially) tested:
1) Superblocks
2) Allocation Groups
3) Inodes
4) Directories, including:
5) ShortForm Directory Headers and Entries
6) Single Extent Directory Headers and Entries

- Additional code that is not relevant at this point has been removed from this pull request.

- Rubocop warnings have been implemented as far as feasible and relevant.

- Some comments from @Fryguy have been addressed.

@roliveri @Fryguy @chessbyte please review at your convenience.