Escape regex replacement string in process_gist_html(). See #32.
Add support for GitHub Updater

Adds support for [GitHub Updater](github.com/afragen/github-updater).

The plugin URI tag points to this repo.
The branch tag is generally optional, but since we follow a git-flow process here (commit to develop, keep master as clean releases), we want to tell the updater to check that branch for changes in Version number and which archive zip to download.

Also removed the trailing slash from the Domain Path, as WordPress trims it away anyway.
Merge pull request #33 from GaryJones/develop

Add support for GitHub Updater plugin.
Fix for oEmbed cache not clearing on update.

Replaced do_shortcode() with apply_filters( 'the_content' in method delete_gist_transients in class GistPress. do_shortcode() does not does not process oEmbeds, which prevented the shortcode method from being executed and clearing the cache.
Fix for oEmbed cache not clearing on update

Replaced do_shortcode() with $GLOBALS['wp_embed']->autoembed() in method delete_gist_transients in class GistPress. do_shortcode() does not does not process oEmbeds, which prevented the shortcode method from being executed and clearing the cache.

This is an improvement over my previous pull request, which used apply_filters( 'the_content' and therefore applied signficantly more filters than necessary.  Thank you to GaryJones for this improvement.
Correct erroneous output from method rebuild_shortcode in class GistPress

Replace $rawattr with $attrs in method rebuild_shortcode in
class GistPress as per @bradyvercher's comment in
[Issue 34](https://github.com/bradyvercher/gistpress/issues/34)

Old Erroneous Behavior: [gist 7243951 1]
New Corrected Behavior: [gist id="7243951"]
Merge branch 'master' of git://github.com/salcode/gistpress into salcode-master
Add missing slash in the plugin text domain path.
Move included classes into an includes directory.
Improved load text domain.

Includes the required textdomain within the .mo file name.

Wraps WP_LANG_DIR in trailingslashit() to ensure two slashes aren't used.

Grabs the path to the languages folder to it better works with symlinks.
Add oembed support for bookmark-format URLs.

Since we can't immediately tell if #file-foo-bar-php meant foo.bar.php or foo-bar.php, we do an API call for the whole Gist which lists all the files. We loop through the files, and take the first one that matches our oembed URL suffix when sanitized.

At the moment, this extra API call is NOT cached at all.
Merge pull request #36 from GaryJones/feature/includes

Move included classes into an includes directory.
Merge pull request #37 from GaryJones/feature/load-textdomain

Improved load text domain.
Merge branch 'feature/bookmark-oembed' of git://github.com/GaryJones/gistpress into bookmark-oembed
Readme tweaks, including a new section about updating.
Merge branch 'bookmark-oembed' into develop
Cache the remote API call in the file lookup method.
Bump tested WordPress version to 3.8 in the readme.