Pass alias suffix to index script, optionally skip aliasing (#191)

This commit fixes an issue with the automatic alias updates: after
indexing lobid-resources, the alias was updated before lobid-items
were indexed into the same index, resulting in an incomplete index
until indexing lobid-items was done.

This commit also simplifies the alias handling: previously, there
was a custom mapping from index names to aliases. Instead, we now
just remove the timestamp from the index name to create the alias.
Merge pull request #312 from fsteeg/issue-191-suffix

Pass alias suffix to index script, optionally skip aliasing