migrating to wildfly

Updated pom and necessary import paths. Using jackson 2.x api.

using the following versions
* java ee 7
* resteasy 3.x
* jackson 2.x
fixed: PekErrorCode serializer unwraps the error object
lazy fetching for all user properties (closes #84)
fixed imports
refactored ConfigurationImpl

using post construct instead of the constructor
loading the environment eagerly
fixed tests after pom update

note to self: a dependency marked provided (scope) is available during
test as well