Streamline initialization of class names in 'java.lang' package.
remove obsolete class.
remove obsolete classes.
- move COM_SAP_JDK_HOME_PATH_KEY constant from DevelopmentConfiguration
  into BuildVariant.
- improve calculation of JdkHomeAlias and don't return null for it 
  anymore. Match against Java version of currently running VM if no
  build variant or path has benn configured.
Use StringUtils.isEmpty(), add tests for equals().
add tests for getJavaHome(JdkHomeAlias): java.home property handling
when no matching JdkHomeAlias has been registered.
unify setting of JAVA_HOME environment variable: use value (correctly)
calculated in DIToolDescriptor.
deprecate AbstractDefaultHandler & XmlReaderHelper in favor of Digester.
Remove DomHelper.
remove class name mapping for java.lang package. Try to load given class
name from java.lang package instead to determine if it exists there.
fix checkstyle warnings.
Clean up activity reading.
remove unused private method componentExists().
Remove dependency to Activity in NWDIRevisionState.
Fix FindBugs warnings in PublicPartReferenceFactory, add unit tests.
Replace XmlReaderHelper usage with commons Digester.
add digester3 dependency.
Extract common functionality into AbstractComponentConfigurationReader.
Change implementation of ConfDefReader to Digester3 and add
comprehensive unit tests.
- Move calculation of default build variant to BuildVariantFactory.
- Cache create BuildVariants in factory.
- make factories static inner classes.
Throw IllegalStateException instead of RuntimeException.