Added HtmlCompressor preserve option

Added a project property specifically for the HtmlCompressor --preserve
argument. Specifying the preserve argument here allows the preserve
file path to be relative to the base directory; otherwise, specifying a
preserve option in tool.htmlcompressor.opts.extra would require a path
relative to the JVM.
Added an example custom preservation rule file

Added an example custom preservation rule file for the new
tool.htmlcompressor.opts.preserve option. The example rule file matches
mutiple lines and looks for head tags. In practice this may not be a
good thing to choose for preserving spacing, but it serves as an
example where the effect is easy to recongize.

Added a reference to the HtmlCompressor documentation with more details.
Using the build directory property for the HtmlCompressor preserve option

Removed build/ from the front of the
${tool.htmlcompressor.opts.preserve}. Instead, ${basedir}/${dir.build}
is concatenated to the front by the build script.
Merge branch 'master' of https://github.com/tommyvernieri/ant-build-script into tommyvernieri-master
Merge branch 'tommyvernieri-master' into 1.1.0