Adding checksum into the DB

[josenavas]

This adds checksum support to the DB. Specifically:

• New table checksum_algorithm with two columns: checksum_algorithm_id and name to store the algorithms used for the checksum generation.
• Two new columns on table filepath: checksum (stores the actual checksum) and checksum_algorithm_id (foreign key to checksum_algorithm table).

The files initialize.sql and populate_test_db.sql have been updated to reflect this changes.

This should be fast to review. @squirrelo, since you've been working a lot with dbschema, it would be great if you can take a look and make sure that I've updated everything correctly. This is blocking further development on any object that modifies the filepath table.

[coveralls]

Coverage remained the same when pulling 8449a38 on josenavas:checksum into a120cce on biocore:master.

[squirrelo]

👍

[wasade]

why index here? It likely won't be any benefit as the data are not unique

[wasade]

or even near unique

[josenavas]

Thanks @wasade
I fixed your comment and the tests passed, are you able to merge?

[coveralls]

Coverage remained the same when pulling a68eb5e on josenavas:checksum into a120cce on biocore:master.