Fixed Template.variable? lookup, added less_than test for variables.

I was using Wongi in another project and realized that Template.variable? was misusing the ```=~``` operator.  The operator returns nil if there is no pattern match, otherwise it returns the starting index of the regex.  Since this regex was looking for the start of the line, even matches were returning ```0``` which would in turn be read as a false.

Also added a test to verify variable comparisons work.