Added an editor to blob file.

[wxbit]

Hi, everyone. I have a patch to blobpage, added an inline editor for plain text file.
Anyone can get the patch.zip, unzip BlobPage.html and BlobPage.class to WEB-INF/classes/com/gitblit/wicket/pages, and replace gitblit-editor.min.js at web root with the one in archive.

patch.zip