#2 More flexible constructor for ConfigurationStore

[Arnout Engelen]

The ConfigurationStore currently mandates a File object to read the configuration.

Afaics, this means the configuration must be stored in an actual file on the filesystem, and cannot be read from, for example, a jar on the classpath.

It'd be much more convenient if there were some more flexible ConfigurationStore constructors, for example one taking an InputStream.