Access control (#31)

* Add initial acl implementation

* Implemented access control with utilities from paritytech::jsonrpc

* Incorrect if

* Make allowed_hosts an enum

* Handling CORS in process_request

* Build for AccessControl and naming coherence

* "clean up your room! clean up your room ! that's all i ever hear..."
- preflight requests
- test and bench
- wasm for yew

* Add basic acl tests for 'host'

* Remove 'macro_use'

* Apply rustfmt to server-utils

* Apply rustfmt to http

* Bump lazy_static dependency