Mixed bag: fixed some issues in tests makefile + added tests for tokenized field-type + added support for json-array subscripting

This patch-set 
- adds tests for tokenized field-type (mmnormalize)
- adds impl + tests for json array-subscripting
- some tests added earlier weren't included in EXTRA_DIST, it adds them to it.

It goes after https://github.com/rsyslog/liblognorm/pull/8