updated data model comments.

Added comments and added boost license to header.
data_model template src moved to tcc.

Moved data_model template operations into new bits tcc file, included by
the data_model.
Merge branch 'db' into cppdb
updated cppdb for current data_model.

1. Updated names of variables and namespaces to match current names.
2. Changed interface to take function pointer as late as possible to
simplfy the interface.
3. Changed cpp src to tcc for template implementation.