Ant build process changes

[ljo]

Robustness changes in the ant build process.

• Make sure rhino runs on 32 bit machines. Eg condition to set rhino optimization to -1 if 32bit property is set.
• Changed rhino url.
• Remove downloaded rhino resources on clean.
• Removing xars in build on clean.
• Adding @failonerror="true" to java task in the xqlint target.
• Adding rebuild target.
• Moving check of availability of rhino and closure to dependency of get-*-target.
• Adding version to index.html and expath-pkg.xml from project.version property on build.
• Optional git.commit id in xar filename.