fix(php): Added matching for shebang headers like #!/bin/php

Should also match:
#!/usr/bin/env php
#!php

Originally proposed in scopatz#386

php.nanorc

@@ -1,5 +1,6 @@
 ## PHP Syntax Highlighting
 syntax "PHP" "\.php[2345s~]?$|\.module$"
+header "^#!.*php"
 magic "PHP script"
 comment "//"
 color white start="<\?(php|=)?" end="\?>"