changed install tachyon to check out from my personal branch.
changed install tachyon to check out from my personal branch.

kcompher/velox-modelserver,henryem/velox-modelserver,amplab/velox-modelserver,amplab/velox-modelserver,henryem/velox-modelserver,samklr/velox-modelserver,kcompher/velox-modelserver,samklr/velox-modelserver,henryem/velox-modelserver