Refactored getJavaVersion() to getCurrentJava()

 * Cache current java version
 * Update code calling getJavaVersion()
 * Renamed some variables
FIXED: use correct java bitness

 * Logging
 * Options pane
Refactored OptionsPane.java code

 * Java warning and JRE download button can be updated after pane creation
 * Changing java path under advanced option will update options
   tab warning labels and JRE download button
 * Moved java warning label
Merge pull request #719 from jikuja/fixes_v3

More fixes