made showdown-extension configurable via commandline and project-json
Merge remote-tracking branch 'nevir/master' into showdown-extensions
Merge branch 'nevir' into showdown-extensions
enhanced pull-request by switching the type of the proposed '--showdown'-option to 'list' and updating `utils.markdownComments` accordingly
added missing colon in the '--showdown' option defintion
shortened '--showdown'-option's description to make 'groc -h'-output less anoying
Merge pull request #97 from sjorek/showdown-extensions

Feature: configurable list of showdown-extensions