Rename `to_json` to `to_json_string`

The method named `to_json` is pseudo-magic in Ruby; the json gem
defines it on every object, and relies on a zero argument `to_json`
method existing on everything nontrivial.  This is too much of a
headache to work around in the Ruby driver alone, so we are forced to
spread the misery and rename the method.

Which is tragic, because it breaks consistency, but that’s life.
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
Reuse `timeout` and `authKey` when reconnecting JS.
Change wording/capitalization
Add aliases for Python and JavaScript
Merge branch 'gchpaco_3123' into next

Fixes #3123.
Use latest Ubuntu AMI as base in build AMI script
allow building with protobuf 2.6.0
Use latest Ubuntu AMI as base in build AMI script
allow building with protobuf 2.6.0

OTS review by mlucy
Closes #3137
Add #3137
Fix debian package version and remove build dependency on node
merging the Python and JavaScript portions of #2912 Float rounding issues on polyglot/geo/primitives
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 'next' of github.com:grandquista/rethinkdb into grandquista-next