fixing behavior when passing a non-directory to --directory
merging #3112 r.http() https access not working on OSX

Conflicts:
	mk/support/pkg/curl.sh
Add 1.15.1 release notes
Updates
committing the configure changes from #3112
Change wording/capitalization
Use latest Ubuntu AMI as base in build AMI script
allow building with protobuf 2.6.0
Add #3137
Fix debian package version and remove build dependency on node
Merge pull request #3135 from rethinkdb/wm-1.15.1-notes

Add 1.15.1 release notes
Bump Python driver to 1.15.0-1
Merge branch v1.15.x into next