Improving theme data gathering on Update
On Issue #241 @fjrrett reported some notices on the theme update page.

The source of the problem there was that the information can be stored
in another variable called `theme_info` and it is a instance of [WP
Theme](http://codex.wordpress.org/Class_Reference/WP_Theme) which the
methods change a bit from what was used.

I've included a conditional to check for the `theme` variable them if is
not set I work with the `WP Theme` instance.
Better them checking if `$action` and `$type` are set, just use a bit later when we are sure that the processing was a success
[connector:installer] Fail earlier if no operation type is detected #241
Fix installer connector not tracking bulk theme update

Fixes #246 and #241
Merge pull request #242 from x-team/issue-241

Improving theme data gathering on Update