This reverts merge request !64

Client now reads host file to determine auto_sm and RPC protocol

Restructuring code w.r.t. configurations and definitions:
- #defines have been mostly removed from configurations
- a dedicated config file has been added for configurations with constexpr
- past configure file is now only a cmake wrapper
- wrapping global functions into namespaces

Removed all adafs and ifs occurrences. Now called gkfs

This commit updates Hermes to v0.4.1 and configures it to generate RPCs
with "instrumentation breadcrumbs" that can be understood by servers
relying on Margo >= v0.5.2. Fixes #72.

CREATE_CHECK_PARENTS controls if the existance of the parent node needs
to be checked during the creation of a child node.

Example: The check prevents the creation of file `/parent/child`
if `/parent` doesn't exists or if it is not a directory

By default CREATE_CHECK_PARENTS is enable and the check is enforced.
It can be disable to speedup creation operations by passing
`-DCREATE_CHECK_PARENTS:BOOL=OFF` as cmake parameter.

Fixes an issue where client applications such as ssh might attempt to
close all open fds, therefore also closing the fds used by the internal
components of the library such as Mercury.

The new `LOG_SYSCALLS` Cmake flag can be used to enable verbose logging of
system calls interception.