JS-98 : mechanism to detect if index need to be recreated by comparing IndexMetadata from prop file for now  Started partially with the patch from Tonny Kohar dated 15/May/09
- Added InstalledIndex.prop file (location of this file TBD)
- Support for PerBookVersion properties

Added InstalledIndex.prop file for "Installed.Index.Version.xx" values that should stay persistent on clients computer
Since index creation api is per Book, added support for (optional) PerBookVersion properties to allow selective upgrade of a per-book index, if needed.

Added basic impl of needsReindexing method to IndexManager. LuceneIndexManagerTest to be used after we can manipulate Installed version values.
Merge pull request #74 from sijocherian/master

JS-98: IndexManager.needsReindexing(Book book); as the API to detect if per-book index need to be recreated