Add D3 Tip for a bar chart with tool tip

The example I am reproducing uses a D3 plugin which adds a nice tool
tip. I will use this to make the bar chart more interactive.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>
Implement bar chart to visualize scores by groups

I have implemented a D3 bar chart example. It shows the scores and how
they are distributed by groups. The idea is to investigate, whether
there are quality differences in the groups, respectively data provider.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>
Fix default identifier for snapshot

A small mistake lead to the possibility of creating duplicate snapshots.
This was possible, because the MD5 hash was based on the returned
Mongoid repository object and not its identifier.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>
Skip empty text in the spelling metric

Empty text resulted in NaN scores for the per metadata record analysis.
Hence, I have added a skip statement to avoid recording these fields.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>
Move record selection into a partial

For the completeness metric view the same elements are needed to display
the records side by side and enabling the user to select and search for
other metadata records. Thus, I have copied the relevant elements into
a separate partial.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>
Start to integrate record selector partial

I have started to integrate the partial with the appropriate yield code
statements. The next step will be the retrieval of the previous
completeness view implementation and copy the table layout code.

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