global: fixes for encoding and tests
global: fixes for encoding and tests

* Changes handling legacy application request object `write` and `flush`
  methods in order to avoid sending headers to early.

* Cleanes legacy application main template to deal with 'utf-8' encoding
  problem.

* Multiple small fixes for making some of the regression tests run
  again.

inveniosoftware/invenio-base,tiborsimko/invenio-base,inveniosoftware/invenio-base,tiborsimko/invenio-base