Add basic hashing of nuc_data.h5

This commit includes functions to generate the hashes for each dataset,
functions to generate hashes using nuc_data_make, and a current hash of
nuc_data.h5 datasets.
Improve PEP 8 compliance
Make hashing functions more concise and move hashes to c++

As was discussed the hashing functions have been made more concise and
combined into a single file. The stored hashes have been moved to
data.cpp and are accessible through pyne.data. Docstrings were also
added.
PEP8 style changes to nuc_data_make

remove lots of trailing spaces at the end of lines and adding spaces
after commas and between +’s.
Use data_checksums instead of hash in c++; remove _ from hashtools.py

In addition made initialization internal to c++
Add basic test of data_checksums
Use relative imports and refactor hash_map to data_checksums
Fix spelling error and try to make automatic merging possible
Merge branch 'staging' of https://github.com/pyne/pyne into hashes
Pull in upstream changes so new ensdf dataset can be hashed
Remove extra blank line needed for automerge
Update checksum for new ensdf data
Move returns outside of with blocks
Add test of internal hashes and guarded pyne.nuc_data use