Support committing Lucene writes within a fixed interval

The ramBufferSize and maxBufferedDocs options control how often the
writer is flushed, but this does not fsync files on disk and thus
might not be permanent, particularly in a machine under heavy load.

Add an option commitWithin to bound the time between calls to commit.
Give each sub-index its own executor to flush and commit outstanding
changes. Non-positive periods trigger commit on every write.

Change-Id: Idfaf17a1eeb9240f25ee1fc842bdf4f8c9b873c3
Release Notes: Set max page width to 55em

This makes the release notes look a bit nicer, and easier to
read, on wide screens.

Note that the max-width attribute is not yet supported in
asciidoctor, so we can't set this for the main documentation.

The release notes are still generated with asciidoc.

Change-Id: Ide83ca20dc61ede16080d017b22435360928877f
Fix a typo in the 2.8 release notes

Change-Id: Id3d031ca7cdc337b3a666c63cb2f4d16a7d646a5
Update the 2.8.2 release notes with recently merged fixes

Change-Id: Id8796338895121472a3b7a4c48646fe086f34c1f
Remove double border around code snippets in documentation

Bug: issue 2480
Change-Id: I8aa10bf28f5881ce5d073dfd214e3f6db796177b
Add border for tables in documentation

Without border the tables (e.g. in the REST API documentation) are
hard to read.

Change-Id: If750c09c8518bac3575ada606e918bf18ccc57bf
Signed-off-by: Edwin Kempin <edwin.kempin@sap.com>
Add another case to the prohibited by Gerrit error documentation

Change-Id: Ie16b7ae361590023939c04e101c120fe98e79aa1
Signed-off-by: Edwin Kempin <edwin.kempin@sap.com>
Fix minor typo in REST API accounts documentation

Change-Id: Icb9fc6ae948468860d9f0d5ac2fff110e183849a
Update the revision of the cookbook plugin

To get the following changes:

- Add Gerrit-PluginName in the BUCK and Maven configs
- Add an example of plugin-owned capability
- Remove unnecessary exceptions from hello command class declaration

Change-Id: I2601b40367bba9e1ecd83adacd3193b9610055b0