There is apparently no reason to ignore empty results - it was probably the case in the past (`null` value).
["", "v"] should be considered invalid by toValue() because it represents two values.
["", "v"] should be returned as it by toValues(), not trimming "".
Tests passes, it will hopefully not cause any issue in prod.
Clair will now use a YAML configuration file instead of command line
arguments as the number of parameters grows.
Also, Clair now exposes a Boot() func that allows everyone to easily
create their own project and load dynamically their own fetchers/updaters.
