This accepts data from the updated backend
(from the previous commit) but does not display
any of the new metadata yet.

This is not tested with search results, because I could
not obtain search results locally. Suggestions on the
home page work, but no results are shown in /search

This makes displaying metadata of an exercise
less verbose. Styling is a bit lacking as of now.

Restructure metadata translations of lists
to make declarations more concise.

added GitlabService.java to offer basic gitlab api functionalities like check if repo exists etc. , added check in StatisticsResource to avoid people sending get requests with IDs which not exist and therefore create lots of trash entities

added additional metadata fields -> difficulty, education level, status, type, version, format, keywords, requirements

At the moment, we only treat exercises as search results,
but exercises can also appear in other context,
e.g. as bookmarked exercises.

For this reason, it makes more sense to describe them
using the more general term "Exercise".

Exchange hard-coded strings for jhiTranslate values.

Metadata still needs to be modified.