Allow searching of adt files on eclipse.local.
Added eclipse.dest property.

New property is used instead of eclipse.local on deployment to make a
clear separation of responsabilities.

Previously, eclipse.local served both as source for plugins in
~/.eclipse and as destination. This might be what is intended on most
situations but in some exotic uses might create problems. For instance,
while setting up my development version of eclim with an Arch Linux
PKGBUILD, I need gant to get plugins from /usr/share/eclipse and
~/.eclipse/org.eclipse.platform_4.2.0_1543616141/ and then install
the compiled eclim plugins to $pkgdir/usr/share/eclipse.