Update tests to shortened API
Rename Appender to gremlinAppender
Move appender from Client to GremlinScript class
Rename gremlinAppender() to appendToScript()

Simplify the way GremlinScript methods are proxied on the appending
function
Update transaction test to check for line count
Rename line to statement in GremlinScript.line()
Expose .append() method
Update README.md
Switch to strict mode