Add a "range" filter

Range is a useful function for python. Would you mind to add this also?
Ref: http://stackoverflow.com/questions/11873570/angularjs-for-loop-with-numbers-ranges

Look at existing filters in the repository to understand the pattern. The filter should generate a range of numbers, similar to Python's range. Check the test files to see how filters are tested, and implement the new filter with corresponding tests.

由索引模型根據 Issue 內容生成。