Merge pull request #1 from prinzmajus/master

Adding Vagrant and QA Pipeline
NOTE about git submodules in README.md added
Merge branch 'master' of github.com:jonaswisplinghoff/arsnova-flashcards
implemented export api call, rough ui integration
*Markdown Editor

TODO:
* Linebreaks
* Markdownsupport in Cardview
Merge pull request #3 from prinzmajus/master

v1.0 final version
Merge pull request #2 from RafaelKa/patch-1

NOTE about git submodules in README.md added
Delete deployment to cloudcontrol
added fileSaver to download json export
*Now shows Markdown
addded json import
depiction of created or edited cards after saving or canceling, instead of always first.

our issue from redmine: #10638
styled input file form
minor design fix
added filetype check
added more useful help popup to import form
* imgbutton disabled
* texbutton
added csv import
some more security checks
Merge commit '3b825cc3faf894ceb5e690d3652347f3470dab6b'