ENH: Miniconda-based testing on Travis-CI

Experimental branch that uses miniconda rather than platform
python to test.  Has some advantages in that it is simple to reconfigure
alternative combinations of NumPy, SciPy, Cython and pandas easily,
at least as long as they are provided by Anaconda.
ENH: Alternative travis script that uses Anaconda via Miniconda

Provides an alternative method to test on Travis using Miniconda
that has some advantages from the current system.

- All binary, so no time spent building
- No branching in the execution steps
- Support for up-to-date requirements which are important to test

Also includes a small change to tools/matplotlibrc which changes the backend
to Agg to avoid Tk-related errors on Travis.  Agg is alays available and does not
depend on Qt or another toolkit.

Closes #1500
Changed build configurations to match those discusses in #1523
Fixed config for Python 3.3
Attempt to inspect segfault
Final fixes to remove redundant code from travis config file
Final fixes to remove redundant code from travis config file
Added 4th build configuration

New configuration will always be on the most current versions using Python 2.7
Fixed conda-related issue which allows for no MKL
Added option for cvxopt to Python 2.7, Numpy 1.7 config
Merge pull request #1523 from bashtage/travis-miniconda

MAINT: Use miniconda on Travis.
Merge remote-tracking branch 'remotes/upstream/master' into warning-convert