Tika server reports it's version as "Apache Tika 1.7". Unfortunately, `version_compare` in PHP says that version "1.7" is less than version "1.7.0", meaning that Tika server was incorrectly being ruled out unless you used Tika server version 1.8 (where "1.8" > "1.7.0").
Changing the comparison string to just "1.7" means they match exactly, and therefore `version_compare` will return `0` rather than `-1`.
- Added namespaces, use statements
- Added missing docblocks etc
- Uses SS4's new Cache system
- Uses proper environment vars
- Cannot instantiate 'FileTextCache' (interface) as a service. This can be configured through YML, so default to FileTextCache_Cache
- Modded YML config to make it run.
- Fixes to allow TIKA to actually get file contents.
- Addresses issues raised by @robbieaverill
- Rebased against github.com/silverstripe/silverstripe-textextraction:master
- Replaced `SS_Log` with Monolog.
