Change code wrapping to only affect literal code blocks.

Hey,

I really like what you have done to get bootstrap working with sphinx, it's fantastic!

I did however have a little trouble, when entering inline code blocks in rest like 
``` rest
``literal code``
```
This behavior is documented in the inline markup section of the sphinx doc
http://sphinx.readthedocs.org/en/latest/rest.html#inline-markup

Any way, so initially made a small patch to add code wrapping to these blocks. But things got a bit complex, because the same markup was being used for xrefs and inline code.  Since inline code blocks don't link anywhere it's a bit of a confusing experience, some are links some are not. So i have instead created a basic patch that changes the wrapping of bootstrap code blocks to only effect the inline code blocks.

Cheers,
Russell