Read capability for NWB 1.x

[ajtritt]

Starting a list of items that will be needed to support reading of NWB 1.x files.

• Extend TypeMap to override the get_cls method. This is needed to determine the neurodata_type for GroupBuilders that don't have 2.x neurodata_type and namespace attributes.
• Create ObjectMappers for the TimeSeries and Interfaces from 1.x. These ObjectMappers should be registered with the TypeMap extension using register_map
• The TypeMap extension, once instantiated, will need to register the neurodata_types from the global TypeMap. Once this is complete, it can be used to create a BuildManager, which can be passed into HDF5IO.

[jcfr]

xref #209

[t-b]

Closed via 936c438.