Obtain dependencies automatically.

I switched from distutils to setuptools. Now, running `python setup.py
install` automatically gets the dependencies from PyPi. I also edited
how the dependencies were listed in setup.py.

Previously, running `pip install cvxpy` did NOT get the dependencies.
Now, if a new release is created for cvxpy, `pip install cvxpy` should
automatically get the dependencies.
Remove get_ecos.sh script.

The script cloned the ECOS repository and installed ecos python package.
However, ECOS is now on PyPi, and it's easy to install automatically
using setuptools.
Merge pull request #35 from chrisdembia/install-requires

Obtain dependencies automatically.