Add new assertions

[dgilland]

• [ ] Iterable - Passes if object is an iterable.
• [ ] Indexed - Passes if object is strictly integer indexed (list, tuple, string).
• [ ] Associative - Passes if object has index or key access.
• [ ] ContainsAny - Passes if object contains at least one element of an iterable.
• [ ] NotContainsAny - Not ContainsAny.
• [ ] ContainsAll - Passes if object contains all elements of an iterable.
• [ ] NotContainsAll - Not ContainsAll.
• [ ] Keys - Passes if object's keys are a superset of given keys.
• [ ] NotKeys - Not Keys.
• [ ] OnlyKeys - Passes if object only has given keys.
• [ ] NotOnlyKeys - Not OnlyKeys.
• [ ] Attributes - Passes if object's attributes are a superset of given attributes.
• [ ] NotAttributes - Not Attributes.
• [ ] OnlyAttributes - Passes if object only has given attributes.
• [ ] NotOnlyAttributes - Not OnlyAttributes.
• [ ] Empty - Passes if object is empty.
• [ ] NotEmpty - Passes if object is not empty.
• [ ] Callable - Passes if object is callable.
• [ ] NotCallable - Passes if object is not callable.
• [ ] Has - Passes if object's values are of any of the types listed.
• [ ] HasNo - Not Has.
• [ ] HasKeysOf - Passes if object's keys are of any of the types listed.
• [ ] HasNoKeysOf - Not HasKeysOf.

[prashnts]

@dgilland: Great library! I am gonna be working on a few of these soon, will send a pull request. :)

Just wanted to ask if using Pydash for these is fine, or should I stick to vanilla/collections?

[dgilland]

Use whatever works best :+1: