removed param "show_noauth"

this as it can be confusing for now, maybe something to be added back
later.
altered checking for http/https in custom fields, FIX #126
altered check of mailer plugin (editevent/editvenue controllers)
changed time of limitdate
event-view:  altered meta_description/keywords retrieval/storing part (backend)
editevent: altered meta_descripion/keywords retrieval/storing (front)
altered access checking eventslist-model
attendees-view(backend):  altered display of print/csv icon
backend css: added icon_print/icon_scv classes
export-view: added missing div
credits: removed some links to urls
help (intro): adjusted line about comments plugin
route: altered functions
Merge pull request #129 from jemproject/dev

several changes