Reuse suggester implementations in suggest parsers
Highlighting shouldn't fail when the field to highlight is absent.

PlainHighlighter fails with a NPE when the field to highlight is marked as
stored in the mapping but doesn't exist in a hit. This patch makes
FieldsVisitor.fields less error-prone by returning an empty list instead
of null when no matching stored field was found.

Closes #3109
Store _version as a numeric doc values field.

Doc values can be expected to be more compact than payloads and should provide
better flexibility since doc values formats can be picked on a per-field basis.
This patch:
 - makes _version stored as a numeric doc values field,
 - manages backwards compatibility: if a version is not found in doc values,
   then it will look into payloads,
 - uses background merges to upgrade old segments and move _version from
   payloads to doc values.

Closes #3103
add 0.90.2 version
Make it easier to get started with Eclipse.

This patch makes mvn eclipse:eclipse generate additional eclipse configuration
files so that Eclipse:
 - uses Java 1.6 compliance level,
 - truncates lines after 140 chars,
 - uses 4 spaces for indentation,
 - automatically adds a license header when creating a new class file,
 - organizes imports the same way as Intellij Idea (which makes sense I guess
   since most of the code bas has been written with Intellij, this will prevent
   from having large diffs due to the fact that the order of imports has
   changed).
Add more information and options in PluginManager
New option -l, --list displays list of existing plugins
New option -h, --help displays help
Deprecate options:
   -install is now -i, --install
   -remove is now -r, --remove
   -url is now -u, --url
Catch ArraysOutOfBoundException when no arg given to install, remove or url option
Add description on plugin name structure:
- elasticsearch/plugin/version for official elasticsearch plugins (download from download.elasticsearch.org)
- groupId/artifactId/version   for community plugins (download from maven central or oss sonatype)
- username/repository          for site plugins (download from github master)
Closes #3112.