bower: upgrade to angular 1.3.0

It seems that if we don't want to force an outdated version of
angular-motion, we need to upgrade to a newer version of
angular. Sigh... Everything seems to continue to work.
bower: upgrade angular-strap to a version compatible with angular 1.3.0
config: use `__` as a separator for environment variables
doc: mention the ability to use environment variables
npm: install mysql and pg connectors if possible

When deploying on a PaaS, we may need them.
npm: currently, we only support node 0.10.x
express: don't use deprecated `app.configure()`
express: use `method-override` module

The express builtin functionality seems to be deprecated.
doc: add some documentation to deploy Dashkiosk on a PaaS

This is not quite working yet.
log: try to get a always get a valid backtrace

When the object throwed is not an Error, we don't get a valid
backtrace. We try to get one by instantiating an Error object in this
case.
log: just display the error object when no backtrace is available

When backtrace is not available, building one with `new Error()` is
useless as the backtrace doesn't told us where the problem comes from
due to use of promises. Maybe logging the err object will get better results.
doc: fix how to specify database hostname

This should be done in `db.options.host` and not `db.options.hostname`.
grunt: allows one to set branding through BRANDING env variable