Add Java installation instructions to INSTALL.OSX.rst

[ci skip]
Add a package.json for managing frontend dependencies

This allows us to install all but compass locally in the project rather
than relying on global executables.
Install frontend dependencies in bootstrap
Update webassets paths in configuration files

These now use project local dependencies rather than relying on them
being installed on the users PATH.
Update INSTALL docs to instruct on node installation

This reduces the number of installation steps for most platforms. Node
installation instructions taken from the Joyent wiki[1].

[1]: https://github.com/joyent/node/wiki/Installing-Node.js-via-package-manager
Merge pull request #1271 from hypothesis/node-modules

Manage frontend dependencies with npm
Merge pull request #1270 from hypothesis/osx-install-java

Add Java installation instructions to INSTALL.OSX.rst
Pin repoze.sendmail until upstream fixes known bug

repoze/repoze.sendmail#31
Add .buildpacks for heroku-buildpack-multi
Remove webassets node binary paths in production

Our common production deployment assumes a heroku or heroku-like
environment. In this environment, the PATH is already set from the
buildpack.
node deps are not development only

Until we start packaging and releasing a version with pre-built
assets, these are needed at runtime.
Add node engines to package.json
Remove obsolete test hacks
Make "make clean" compatible with OSX

Previously it used "rm -r" to skip running the command if nothing was
piped in via stdin. The -r flag is not supported by OSX so now we just
use the find command to perform the removal using -exec.

[skip ci]
Merge pull request #1273 from hypothesis/make-clean-osx

Make "make clean" compatible with OSX
Update uri mapping

To move away from ES query_string, new mapping for the uri fields
should be introduced.

For the index_analyzer we use the pattern_capture filter to be
able to split the uri field to our desire. Some stop words were
added to remove the common not relevant tokens.