feat(dependencies): Automate dependency gathering

Any files matching the globs 'src/app/**/.dependencies.js' and
'src/common/**/.dependencies.js' will automatically have their
dependencies merged into the bower.json file, and the list of
vendor_files that is used during the build process. Further work could
be done to have bower prune and then install dependencies as part of
this process.

chore(less): Move less importing process into its own file
'build.styles.js'

The automated less importing process has been pulled out of Gruntfile.js
and into its own file 'build.styles.js'. This file is now imported into
the Gruntfile when required.

chore(build): Move common utilities to 'build.utilities.js'

Some generally useful utility functions were identified in
build.styles.js. So they were moved into a utilities module
'build.utilities.js' and imported into the Gruntfile when required.