Merge pull request #200 from pranavparikh/master

Import descriptor
adding key object, and improving error messages.
Merge pull request #201 from proverma/master

adding key object, and improving error messages.
Preparing for v0.5.0
Merge pull request #203 from pranavparikh/master

Fixing call for setSSL
Fixing demo tests for import descriptor
Merge branch 'master' of https://github.com/pranavparikh/arrow
Merge remote-tracking branch 'upstream/master'