package: add test.js as npm test script

Also, make it print something on success, its comforting.
Remove unnecessary function export from binding

Removing it allows the Persistent<> to be removed, and the APIs around
persistents are more complex in v0.11. Also, removed unnecessary
`function(){...}();` wrapper around module (node does that itself).
Removed unused ObjectWrapper base from Syslog
Remove assumptions about string size and encoding

AsciiValue and WriteAscii don't exist in v0.11 (and didn't return ASCII,
it returned 8-bit binary and mangled multi-byte character sequences).
Also remove 1K limit on log name, and limit scope of persistent storage
to the open() function.