Resolve "answer statistics (template)"

Closes #112

See merge request swtp-block-ws17/arsnova-angular-frontend!82

Resolve "content types (classes)"

Closes #109

See merge request swtp-block-ws17/arsnova-angular-frontend!86

Select first content (due to array as return paramter)

Remove unnecassary api call for room to get room id (?!)

Re-arrange AnswerOptions (code style)
Add constructor for content
Refactor ChoiceContent
Refactor TextContent

Resolve "content types (classes)"

Closes #109

See merge request swtp-block-ws17/arsnova-angular-frontend!83

Resolve "content creation (text) followup"

Closes #100

See merge request swtp-block-ws17/arsnova-angular-frontend!75

Add constructors for all contents

Resolve "See reed comments (participant)"

Closes #130

See merge request swtp-block-ws17/arsnova-angular-frontend!77

Resolve "Filter content answers"

Closes #122

See merge request swtp-block-ws17/arsnova-angular-frontend!80