WIP: fragile and not working

Writing high level wrapper for HTTP
WIP: foundation

* initialization for requests
+ redirections
+ headers
* setting callbacks through funcs (TODO: remove them also from setopt)
Fixed redirection tests
Merge branch 'refs/heads/master' into dev
Updated to nightly
Merged all tests into one exe
Removed test binary from Cargo
Renamed HTTP methods
Ignoring Cargo artefacts
Fixed warnings in original tests
WIP: processing downloads

* write callback gets a closure instead of dumb object as user data. Failed to pass ptr to trait. Probably should get back later
* cleaning up ptrs to closure immediately after processing
Dropped errors enum, added constants

Error code + message should be enough, there is no need to hide curl deep behind as this is actually only wrapper, not a general http engine