Allows integrators to configure which fields should be used to produce
field "content" for indexed pages.
Before only "bodytext" was used. This is now configurable and "header"
was added to defaults.
Resolves: #134
Fetch sys_language_uid from database.
Until now we did not fetch system related fields from database. As there
is now a RemoveProcessor, integrators are able to remove fields.
Also providing this field enables basic multi language support.
Relates: #25
We use the cache clear hook to index pages whenever the cache was
cleared.
This makes it possible to cover some cases like changing content on a
page. But also if an integrator configures to clear additional pages.
This is limited as we can not handle cache tags at the moment.
Resolves: #131
Do not limit integrator in possibilities to configure.
Therefore previously configure facets for a field need to be adjusted to
contain full configuration for elasticsearch. See changelog.
Resolves: #120