api: configure datasources via loopback-boot

Move the configuration of datasources to datasources.json,
add environment-specific configuration files.

Modify api/app.ap.js to setup datasources via loopback-boot.
html5: enable sourcemaps in debug env
html5: load datasources from datasources.json

Modify configure.js script to merge all datasource config files
and create a single browserify-enabled file.

Modify html5/app.html5.js to dynamically register datasources
provided in the config file.

Modify configuration of the `watch` task to include json files in
the change detection list.
Load models from models.json

Move the definition-releated code from models/*.js to models.json.

Modify api/app.api.js to load modes via `app.boot`.

Modify html5/configure.js to generate a script that will register
all models and statically require() all models/*.js files.
Define client-only models in `html5/client.models.json`.

Rename client datasources:
    remote -> db (match shared models)
    memory -> local
html5/configure: add TODOs
html5: move datasource loader to generated script

Move the loop defining all data-sources from hand-written
html5/app.html5.js to the code generated by html5/configure.js.

This new way is consistent with how models are loaded.
Get rid of ::ref:: in datasources.js generator

Upgrade loopback to 2.0.0-beta3.

Simplify html5/configure.js and remove the hack to convert `"memory"`
to `loopback.Memory`, since the built-in connectors are registered
in `app.connectors` now.
Merge pull request #7 from strongloop/feature/generic-setup

Make the project structure more generic