1. Resolve replicate bug.  2. Cache collections, encapsulate URL generation
Merge branch 'master' into edwFile2
Merge branch 'master' into edwFile2
Merge pull request #28 from ENCODE-DCC/edwFile2

Edw file2
Try to fix travis by only updating the postgres repository.
Add test to show use of schema property dependencies
Make read_length and read_length_units co-dependencies, removing default for read_length_units. Refs #666.
Merge pull request #31 from ENCODE-DCC/read-length-units-666

Read length units #666
Don't capitalize construct tags, document descriptions/captions because of eGFP. #326.
Merge pull request #32 from ENCODE-DCC/egfp-capitalization-326

Don't capitalize construct tags, document descriptions/captions because ...
I limited the columns for 'files', 'replicates' and 'libraries' collections.
Had to make small change to make all the test work!
Added few more columns on Ben's request!
Handle missing biosamples on experiment page, closes #788.
Merge pull request #35 from ENCODE-DCC/r2-hotfix-785

R2 hotfix #785
Merge pull request #36 from ENCODE-DCC/renderless-experiment-788

Handle missing biosamples on experiment page, closes #788.
Merge remote-tracking branch 'origin/master' into ui-tweaks