Add support for name attribute on filters

[dylanlgs]

This Pull Request adds support for including a name attribute on a filter. The use case is running tests written in Gherkin; the name attribute allows us to use a native method for filling a form field with a specified value.

For example:

#...
When I go to the shoes page
And I enter "Nike" in the brand field
Then I should see #...

[coveralls]

Coverage remained the same when pulling e0553c9 on dylanlgs:filter-name into c83e219 on esvit:master.

[esvit]

OK, I'll add this feature, but you must been add your code in source files, not ng-table.src.js because it build automatically. I think I describe development process in readme.

[dylanlgs]

Maybe I'm missing something, but I don't see a contributor guide in readme.