Dev install instructions

OK, here is an explicit recipe to install Blaze.  It's long but should be copy-pastable and should be robust to Python versions and (I hope) platforms.

I've tested this on 2.7/3.4 on my system.  I expect that it fails on some other configurations.  

@talumbau when you have a chance can you see if this is clear and works for you?
Yeah, Python2's `csv` module actually fails just at parsing some unicode files.  This was particularly a problem for the XData employment dataset.  `unicodecsv` is a drop-in replacement that *does* work and makes things work fine, but it's considerably (4x?) slower.  It would be nice to find something else that worked in a streaming way and didn't coerce types.  Maybe something in the Pandas toolchain can be leveraged here.