Merge pull request #3 from Turbo87/grunt

Use grunt to linting and running tests
Moved encodeNumber() and encodeSignedNumber() into PolylineUtil class
Simplified encodeNumber() method
Renamed methods to encodeSigned/UnsignedInteger()
Replaced precision parameter by opt_options in encode/decode() methods

Set opt_options to an integer still works for legacy reasons.
Added factor attribute to options
Added encodeDeltas/Floats/Signed/UnsignedIntegers() methods
Added dimension attribute to options
Added decodeSigned/UnsignedIntegers() methods
Added decodeFloats() method
Added decodeDeltas() method
Simplified encoding and decoding methods
Reduced jshint bitwise ignorance scope