fix an error of varible declaration

var body_after --> var query_string
Fixed an error in older versions of IE

MQ.removeQuery threw a null error in older version of IE because old IE
not support Array.properties.indexOf. more info here:
http://kangax.github.io/es5-compat-table/#Array.prototype.indexOf . the
fix does'nt seem to throw a new error in other browsers.
Add  removeQuery test and standardization

Add  removeQuery test in index.html.
standardization:
I have modified my code to be complied with your standards
e.g. Use 4 spaces to replace tab spacing.
Merge pull request #18 from chenzhenxi/master

fix an error of varible declaration  and an error in older versions of IE