#3 Add details when throwing ConfigurationNotFoundException

[Anonymous]

When exception is thrown:

com.germinus.easyconf.ConfigurationNotFoundException: Error reading configuration for lbtr: The base properties file was not found

it's not entirely clear which file is misssin (also happens when missing global-properties).

It'd be easier for newbies to know which property file is being searched, and not found, to have the filename searched in the message, as well as which location is finally being searched (this may be harder to implement).