Install dump1090 support files in a reasonable place

* Install dump1090 and faup1090 to /usr/bin (It's Linux-standard, not my
first choice.)

* Build dump1090 to expect HTML and Javascript files in
/usr/share/dump1090/public_html

* Make 'make -f makefaup1090 install' install the dump1090 HTML and Javscript
files in the above directory.

* With this build style dump1090 can be invoked from anywhere and it will
find its files.