Refeat HTTP interface

[brenocq]

Is your feature request related to a problem? Please describe. Today http requests are being made using cpprestsdk, but the project is not building properly for Windows and MacOS.

Feature description we want atta to implement the http interface, so that it is easy to use and we can change the underlying implementation in the future if necessary.

Tasks

• [x] Decide if should continue using cpprestsdk or change to another library
• [x] Fix build in Windows and MacOS
• [x] Implement http interface
• [x] Json parser
• [x] Json dumper

[brenocq]

Change from cpprestsdk to cpp-netlib in commit be83a6b3fc90ba1eff15f7e5db532b6f2de3611e. The .cpp file with the Http implementation is being chosen at compilation time (.h is always http.h).

• httpNet.cpp: if it is building for the web
• httpCppNetlib.cpp: if it is building with cpp-netlib support
• httpNull.cpp: if network is not supported