Improve query API

Group pacakges by name and list available package versions
in a versions list.

Include nodes where a package is installed when querying for a single
package.

Signed-off-by: Christoph Kassen <c.kassen@telekom.de>
Update testcase for updated package detail query

Include updated test case for the new package detail
query api.

Signed-off-by: Christoph Kassen <c.kassen@telekom.de>
Merge pull request #15 from TelekomCloud/feature/api-improvements

Feature/api improvements