Adds support for devDependencies

If we can not find the module in bower's `dependencies` list we try in
bower's `devDependencies` list. Only then do we skip if it isn't in
there.
Adds a bower.json for testing devDependencies
Adds base62 to bower_components
Adds a spec for devDependencies
Merge branch 'add-devDependencies-support' of github.com:sukima/debowerify into sukima-add-devDependencies-support
support for bower devDependencies via @sukima