Support headers

• support the global and request level headers
• bump dep version

bugfix

v0.1.13

fix patch import

Add Group

group = Group("/books")

class Client(RequestsClient):

    @group.get("/{id}")
    def get(self, id: int):
        ...

bugfix

bugfix for querystring parser.

bugfix

v0.1.7

fix urljoin

v0.1.3: Merge pull request #6 from ponytailer/raw-resp

support raw resp