Allow setting compileDebug and debug globally

[torvalde]

parse method:

var options = options || {} , open = options.open || exports.open || '<%' , close = options.close || exports.close || '%>' , filename = options.filename , compileDebug = options.compileDebug !== false , buf = "";

Since we can set the open and close tags globally, I think we should be able to set the debug params also....

[TimothyGu]

Please track this bug at mde/ejs#43.