Also, add -Werror to tests so that no warnings in tests are reported anymore.

Remove allow-newer:*, allow-older:* in cabal.project file and instead
list these explicitly. This is a big step for managing dependencies.

Remove the calls to `recvMalloc` in favour of using the (patched) `recv`
from the original nanomsg library, which shouldn't segfault anymore. The
reason for using `recv` are a few, but mostly the fact that `recv` can
allocated arbitrary-long payloads data (up to the 1MB limit) without an
hardcoded limit like `recvMalloc` was imposing. Furthermore, `recv` does
resource cleanup for us via `c_nn_freemsg`, whereas `recvMalloc` is not
thread/exception safe. Consider the implementation:

```
recvMalloc :: Receiver a => Socket a -> Int -> IO ByteString
recvMalloc (Socket t sid) numBytes = do
  ptr <- mallocBytes numBytes
  -- receive by blocking the thread
  len <- c_nn_recv sid ptr (#const NN_MSG) 0 -- (#const NN_DONTWAIT)
  str <- C.packCStringLen (castPtr ptr, fromIntegral len)
  free ptr
  return str
```

If any exception (synchronous or asynchronous) strikes _before_ the call
to `free`, we would be leaking C memory.

Also, throttle messages to avoid flooding the client

It integrates servant-routes which allows to list and export the
server backend routes.

This commit moves `GargConfig` and the other config-related
data structures back into gargantext, so that they can be edited
and expanded without needing to worry about the prelude project.

This commit extends the reverse proxy for the microservices so that it
would serve a custom `/config` file which would contain the correct
baseUrl to initialise the websocket connection correctly.

Still needs to fix some hardcoded URLs. The problem with websockets is
that they use the first URL fragment to determine the documentId,
therefore we cannot proxy to `http://localhost:8009/notes/<frameId>`
because the underlying WS connection will use `noteId=notes`, which is
wrong.