Merge pull request #240 from hanke/openfmrids

Direct support for loading data and design from openfmri.org-style datasets
NF+RF: Report model description from model_key.txt
RF: Discontinue use of deprecated function in the docs
RF: Move boxcar modification from the cmdline into the Python API
BF: OpenFMRI loaded subject model by task ID, needs subject ID
BF+DOC: Fix docs, make run-time test for OpenFMRI schema assumptions
BF: Keep subject info in modeled dataset

Use-case: Load multiple subjects at once. Modeling will be done per subj
run, but no subject info remained in the returned set of datasets.
RF: Factor out location information

In anticipation of changes in the OpenFMRI specifications. Now we have
fewer places that make explicit statements about path hierarchy and
filenames.
ENH: Simple accessor for motion estimates
NF: Load arbitrary features/attributes for BOLD timeseries.