PXD-1992 ⁃ publish dictionary and schema to S3

[philloooo]

These slow-responding endpoints needlessly load sheepdog and peregrine - tying up threads that could be serving user requests:

• https://dev.bionimbus.org/api/v0/submission/_dictionary/_all
• https://dev.bionimbus.org/api/v0/submission/getschema

Let's patch dictionaryutils/travis to publish pre-computed dictionary and schema results to S3 along with the other dictionary files, then patch the reverse-proxy to serve those routes directly from S3.