Fixed some integration bugs
 * On bag merge, hashes were not cloned resulting in sharing instances
   which resulted in strange bugs like changing defaults bag when
   merging the current one with the all one.
 * On merge, pure hashes were not converted to bag resulting in the lost
   of indifferent access.
 * On set, pure hashes were not converted to bag resulting in the lost of
   indifferent access.
 * Now, every value entering are converted at a single location, in the
   []= method.
Improved a bit README
 * Overview is now the Quick Start and explanation in greater details
   how to access parameters.
Improved vagrant commands
 * Commands now implement synopsis statis method.
 * Improved a bit usage test of vagrant user command.
Improved a bit array merge strategy section in README
Fixed Vagrant config implementation
 * The implementation of the Config V2 class was not having a correct merge
   implementation which was causing commands to not have the final
   merged configuration. This is now fixed and merge order seems respected
   and good.
Improved error handling of vagrant user commands
 * When object config.user cannot be retrieved, prints an error message
   instead of creating a new default one.