Log Message:
Update ruby-rugged to 0.21.4.

## Rugged 0.21.4 (January 18, 2015) ##

*   Update bundled libgit2 to 0.21.4.

    See https://github.com/libgit2/libgit2/releases/tag/v0.21.4 for a list
    of fixed issues.

    *Arthur Schreiber*

## Rugged 0.21.3 (December 18, 2014) ##

*   Update bundled libgit2 to 0.21.3.

    See https://github.com/libgit2/libgit2/releases/tag/v0.21.3 for a list
    of fixed issues.

    *Arthur Schreiber*

## Rugged 0.21.2 (November 16, 2014) ##

*   Update bundled libgit2 to 0.21.2 (from 0.21.0).

    See https://github.com/libgit2/libgit2/releases/tag/v0.21.1 and
    https://github.com/libgit2/libgit2/releases/tag/v0.21.2 for a list
    of fixed issues.

    *Arthur Schreiber*

## Rugged 0.21.1 was not released ##