Updated readme.md to reflect alpha status

Addresses #497
Fixed numpy namespace bug in plots.py
ENH: Added option find_MAP to glm().
Fixed a couple more namespace bugs
Merge branch 'master' of github.com:pymc-devs/pymc
Fix short test runs for several examples

This fixes examples where passing `short` to `run` didn't have an effect
because the number of iterations was hardcoded in the `sample` call.

The length of the short run in GHME_2013.py is increased so that slicing
the trace object to burn the first 100 iterations does not lead to an
error when it is passed to `traceplot`.
Merge pull request #498 from kyleam/fix-short-example-tests

Fix short test runs for several examples
Updated .gitignore
Replaced Model.AddPotential with named Potential function
BLD: Remove broken nose-timer.
Merge branch 'master' of github.com:pymc-devs/pymc
Replaced Model.AddPotential with named Potential function
Added Weibull and half-Cauchy distributions
Merge pull request #513 from pymc-devs/potential

Replaced Model.AddPotential with named Potential function
Improved docstring for scipy_exponweib_sucks
Merge pull request #517 from pymc-devs/distributions

Added Weibull and half-Cauchy distributions and tests