require at least version 0.3.4 of oauthlib

Hi,

I tried to use requests (1.0.4) & requests-oauthlib (master version) and faild on my Ubuntu 12.10 system.

After a bit of investigation I found that the python-oauthlib package is of version 0.3.0 while requests-oauthlib imports certain things from oauthlib.oauth1 that only became available in version 0.3.4 of oauthlib.

The pull requests makes the dependency more explicit.

--
Misha