switch from jackson-1 to jackson-2

The aws-java-sdk pulls in jackson-2 so
right now using archaius with that lib
will result in both versions getting used.
With this change only jackson-2 would
get pulled in.
Merge remote-tracking branch 'nflx/master' into jackson-2
Merge pull request #204 from brharrington/jackson-2

Jackson 2. Thanks @brharrington again for the contribution!