add chai assertion library as dependency

needed, since mocha doesn't have assertions
add globals for mocha (describe and it)
add first spec file for local files middleware
separate jshint config for specs

specs need a separate jshintrc, since chai needs '"expr": true' option
because of https://github.com/chaijs/chai/issues/41
move some shared tests into a shared lib

every middleware of appserver has some API in common, this can be tested
with shared examples