More db changes

[squirrelo]

Changes:

• Added analysis_chain table to analysis group. Keeps track of the analysis network as discussed today with @wasade @adamrp @josenavas
• Added analysis_filepath table to analysis group. Links an analysis with its filepath entry in the main filepath table. (Mainly biom tables)
• Added job_results_filepath to analysis group. Links a job with the resulting filepath entries in the main filepath table.
• Added study_preprocessed_data table to link a study with it's preprocessed data entry. Needed because one raw data file can belong to multiple studies.
• Heavily rearranged schema to make it pretty 😄

[coveralls]

Coverage remained the same when pulling 55917bf on squirrelo:moredb into 8371d7d on biocore:master.

[josenavas]

👍

[squirrelo]

Anyone? Need a second set of eyes on this. This is blocking development.

[teravest]

looks good to me

[josenavas]

Thanks @teravest

[squirrelo]

Thanks @teravest!