Made compatible with lucene 4.4

In lucene 4.4 (which the latest release of elasticsearch (0.90.5) depends on, the ReusableStringReader has been refactored out from the Field class, and changed it's package to the analysis.

This pull request contains the fixes needed to get the plugin to build with lucene 4.4. There are also some changes in the pom regarding versions to keep these apart, but I suspect that you will want to change that =)

Thanks for maintaining this project!