fix mac installation issues:

* add pyOpenSSL to requirements;
* use psutil for get_num_fds;
* handle cases when RLIMIT_NOFILE can't be increased to hard maximum
move pyOpenSSL to test requirements and add openssl to a list of required Debian packages
fix test running for OS X 10.8

It used to work on OS X 10.7, but in 10.8 splash requires
more time to start and this makes all tests fail.
remove PyQt from requirements because it can't be installed using pip; replace PIL with Pillow
gitignore
Merge pull request #11 from kmike/mac-installation

fix mac installation issues