add puppet agent for pfSense

Finally, a puppet agent for pfSense!

- tested on pfSense 2.1.2 amd64 (should work on i386 and 2.2 too)
- includes some GUI components to configure the puppet agent
- dependency converters/ruby-iconv requires DEPENDS_CLEAN="" in build_options for a successful PBI build on FreeBSD 8.x and 9.x (see [1] and [2])

[1] https://github.com/pcbsd/pcbsd/blob/master/src-sh/pbi-manager/pbi-manager#L1817
[2] https://github.com/freebsd/freebsd-ports/blob/master/converters/ruby-iconv/Makefile#L34