Add read_rdump and stan_rdump

The tests for these are thin. Consider the functions experimental.

Closes #63 and #65.
DOC: Add documentation for stan_rdump and read_rdump
API: Make read_rdump and stan_rdump available underneath pystan
Store PyStan version information in a single place
Allow data to be OrderedDict in addition to dict
TST: Use binary versions of required packages to speed up travis-ci
BUG: Passing pars to sampling limits parameters saved.

Closes #64
Partial fix for zero length parameters.

Suppose one passes n=0 as data to the following model:

    data {
      int<lower=0> n;
    }
    parameters {
      real a0;
      real a[n];
    }
    model {
      a0 ~ normal(0,1);
      a ~ normal(a0,1);
    }

fit.extract() is broken in this case, but fit.summary() and other methods work
fine.
BLD: Require and test against NumPy 1.7 or higher.

Versions earlier than NumPy 1.7 do not support Python 3.3.
BLD: Remove unnecessary files from source distribution
Prefer explicit keyword parameters.
Use param_dims_oi appropriately.

Closes #74
FMT: Remove trailing whitespace
Merge branch 'feature/issue74' into develop
API: For fit instances, repr returns same thing as str

Mirrors convention for DataFrames in pandas. Closes #73.
DOC: Add Windows installation instructions.

Thanks to Patrick Snape.
DOC: Consistent headline case
Fit instance plot method accepts string (rather than list)
Merge branch 'feature/plot-bare-parameter' into develop
It's a team effort