ENH: RSA implementation with tests.

This is the RSA essence of PR #121.
DissimilarityMatrixMeasure returns multi-samples, one feature

unless squareform.

TODO: make the return dataset more sexy, e.g. record pairs...
BF: DissimilarityConsistencyMeasure: one feature/multiple samples in return

Now the tests should pass.
DOC+RM: Make RSA docs more similar to the rest; kill DissimilarityMultiRegressMeasure

The removed class had no tests. Can be reintroduced later on.
RF: Kill all broken, half-baked and duplicate RSA implementations.

Also killed the searchlight_dsm example -- long broken and not very
meaningful anyway. Needs replacement.
BF: Guard for missing scipy
ENH: Add sample attributes to DSM results
OPT: Avoid repated vstack'ing and associated copying.
ENH: Improve DissimilarityConsistencyMeasure

with attributes, a bit of speed-up, support for square corrcoeff
results, and associated tests.
RF: TargetDissimilarityCorrelationMeasure returns more features

Though to argue why rho and p would be samples.
DOC: Draft of an example for the new RSA code.
DOC: Fix up docs
RF: Convert RSA class args into proper parameters.

Sweet liek chocolate!
RF: Rename new RSA classes into something more compact.
Merge pull request #187 from hanke/andy_rsa

Just Andy's RSA implementation