use $*EXECUTABLE_NAME instead of hard-coded 'perl6'

Because we now have perl6-p and perl6-j binaries.
Merge pull request #60 from FROGGS/master

use $*EXECUTABLE_NAME instead of hard-coded 'perl6'
cleanup path to pass use it in substr

See http://irclog.perlgeek.de/perl6/2013-11-25#i_7914075
run custom build method before finding files to install
Merge pull request #65 from Rotwang/master

run custom build method before finding files to install
Update to newest JSON::Tiny

should fix the bootstrap on perl6-j
Get rid of warnings in tests, timotimo++
Update JSON::Tiny
Merge pull request #62 from FROGGS/patch-1

cleanup path to pass use it in substr
Make "panda info" output nicer and more useful. Closes #49
Update File::Find