Add the option to add comments from the changeset screen.

Create a new view in Backbone for handling it.
Added the option to insert comments in changesets.

* Created a new template file for comments in changesets.
* The template comments-for-a-line to comments-for-a-line-file (now only contains the template for comments in files)
* now the template of CommentsForALineView View is passes as a parameter on instantiation
Fixing whitespace issues.

Deleted appearances of several linejumps in a row
Refactored the views for displaying the comment bubble to a LineCommentBubblesView
Fixes #1. solved a bug whereby comments are not shown in the correct line
README.md updated to the latest changes

Added a new element to the features section explaining the inline
comment on changesets feature
Move the logic for setting the template of CommentsForALineView to the initialize method

doing this:
* the logic for setting the template is in the right place.
* uses the default property this.template instead of this.options.template.
* avoid parameters in the instantiation.
Enhanced the way the comments are stored in the DB

* Added a new "page" field to the db ("browser"|"attachment"|"changeset")
* Updated the way Comment.is_comment_to_* properties are created
* Added the filename for comments in commits
Solved spacing issues in the diff table when the comment bubble appears
Fixes a bug whereby the comments in green lines are not displayed.

solves pepegar/trac-code-comments-plugin#2.
Minor changes to avoid changing the value of CodeComments.path.

Used a third argument "file" in the call of AddCommentDialog.open() that contains the
filename of the file we are commenting on, so we can still have a path without changing
any of the properties of CodeComments.
Updated the upgrade process

creates the new column and converts the old comments to the new schema.
Changed the sql statement to query only the mandatory fields
Refactorized the views to try to avoid conditionals with CodeComments.page as much as possible.
typo
Shows the changeset comments in the file screen.
Reverted the changes in the last commit.

Changeset comments in the browser doesn't make sense.
fixed bug where not all changeset paths were being matched
typo fix (arrachments->attachments)
Fix "undefined" filename when commenting on a changeset