Delete obsolete files

Delete obsolete files

- Redundant copies of HTML files used in AspectJ installer, which
  already exist as resource files in module 'build'
- Null-sized AspectJ library JARs which probably were used to trigger
  certain build steps in the former Ant build
- BridgeVersion.java.txt, which has been replaced by a regular
  org.aspectj.bridge.Version class which can dynamically determine
  versions from a properties file instead of relying on them being
  hard-coded into the template.

Signed-off-by: Alexander Kriegisch <Alexander@Kriegisch.name>