Merge pull request #456 from mrocklin/boolean-fixes

expr: boolean fixes
into: error message
into: list <- dict_items (python 3)
Merge pull request #457 from mrocklin/bcolz2

Add BColz and chunking backend
into: exhaustive n by m test
into: np.ndarray maintains type information
into: nd.array <- Table passes dtype/datashape information
into: bcolz.ctable <- Table(list, ...)
into: np.ndarray <- DataFrame using to_records
into: list <- dynd uses tuple=True
into: rearrange optional imports
blaze imports are non-optional
import h5py, avoids pytables segfault
into: bcolz.carray <- dynd.nd.array uses fixlen strings
into: DataFrame <- ctable

Also rearrange columns in exhaustive test
into: nd.array/ctable <- ctable
remove old assertions about bokeh's presence
into: ColumnDataSource <- list, numpy, dynd, pandas, bcolz
docstring for into
into: numpy <- list py3 compat test