Respect the JAVA_HOME environment variable

When the JAVA_HOME environment variable is set, use it to find the java
executable for launching java subprocesses.
Update ReleaseNotes for JAVA_HOME change
Fix unit tests broken by 93961744c
Merge pull request #422 from jonrward/respect-JAVA_HOME

Respect the JAVA_HOME environment variable

Conflicts:
	FitNesseRoot/FitNesse/ReleaseNotes/content.txt
Improve code quality for wysiwyg editor.
Set max height for Add menu in bootstrap theme.
Only templates ending on -Page show up in Add menu.
Fixes #426.
Merge branch 'master' of https://github.com/unclebob/fitnesse.git
javaExecutable did not support JAVA_HOME folders with space in it, for example "Program Files".
Added wrapping into double quotes if space is present in JAVA_HOME.