Added stringContains method, usage: stringContains(searchString,
findString);

Renamed file.js to files.js, added more advanced reading, writing, and
copying based on Apache commons io.

Usage:
var f = files.open(filename, flag [r, w, rw, w+, rw+])
f.write(string)
f.writeLine(string)
var filecontents = f.read()
var nextword = f.readNext()
var nextline = f.readNextLine()
bool f.hasNext()
bool f.hasNextLine()
files.copy(souceFileString, destFileString)