Merge pull request #148 from HazyResearch/ce_

paleo doc
Merge pull request #150 from HazyResearch/ce_

broken links
Do not require deepdive to run in DEEPDIVE_HOME

- Developers can specify environment variable DEEPDIVE_HOME and run
deepdive anywhere. If not specified, deepdive will treat current
directory to be DEEPDIVE_HOME (which is backward compatible)
Use user.dir instead of '.'; Added docs for DEEPDIVE_HOME
Merge branch 'hotfix-ddhome' into develop