fix deep_clone bug

fix deep_clone bug: if obj is a function, not need to clone, it is ok to return it not to clone it .
fix deep_clone bug

fix if obj is a function, not need to clone, just return it not to clone it
 merge two 'if' into one

accept the owner's suggestion, merge two if into one
Update tools.js
Update tools.js
fix less version > 1.3.3 throw error

fix less version > 1.3.3, when the demo run, it will throw an error: "TypeError: Cannot call method 'toCSS' of undefined".
Merge pull request #10 from winnieBear/master

fix deep_clone bug