Update to new style side bar style for dialogs.

This pull request adds a new stylized side bar to any dialog that inherits from QgsOptionsDialogBase.  The main changes are: 

 - New blue-grey with white text style dialog
 - Side panel runs top to bottom
 - Icon size is read from settings

The main reasons for changing this are 

 - make the dialogs look a bit more stylish rather then just a bunch of widgets thrown on a dialog. 
 - separates the page selector to page itself.  Pages on left, and options on right.
 - IMO this makes it easier to focus on the real options on the right
 - Running top to bottom with no border is done in order to make feel different to the rest of the options on the right so the user can focus on them rather then the pages widget.

**Vector layer dialog**
![image](https://f.cloud.github.com/assets/381660/1844709/48a0cc9a-754b-11e3-8855-6c8b52af1717.png)

**Plugin Manager**
![image](https://f.cloud.github.com/assets/381660/1844713/92284b72-754b-11e3-8011-0c0c48369e1f.png)

**Options**
![image](https://f.cloud.github.com/assets/381660/1844715/aa58cce4-754b-11e3-8c62-c494f89caece.png)

**Raster**
![image](https://f.cloud.github.com/assets/381660/1844716/bbf7c356-754b-11e3-820f-44693d7b8498.png)

**Compare**
![image](https://f.cloud.github.com/assets/381660/1844709/48a0cc9a-754b-11e3-8855-6c8b52af1717.png)
![image](https://f.cloud.github.com/assets/381660/1844717/f243ea84-754b-11e3-8795-10abbfb7943e.png)

General feel from people so far is that most like it.

I will leave this pull request open for a few days for comments then merge if there are no strong objections.