Remove pry-debugger and use current pry-byebug

I have uninstalled pry-debugger. This is not visible in this commit,
since it was not part anymore of the Gemfile, but on my local machine.
Pry-byebug works sufficiently reliable, also with the current version.
Thus, I have removed the freezed versioning.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>
Change heading of the second importer dashboard

Instead of metadata the entity to be titled is snapshots. I have changed
the title and the icon.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>
Style repository show view and add range slider

I will move the weighting into the table itself. I have styled the table
a little bit more and inputs of type range are now generated for each
metric row.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>
Start to refactor metric views

I have started to refactor the metric views. I am currently rewriting
the whole metadata record queries. In essence, it is again a lot easier
than with Elasticsearch and tire.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>