Move config parsing code to config.ml

Signed-off-by: John Else <john.else@citrix.com>
Add type Config.config

Signed-off-by: John Else <john.else@citrix.com>
Don't reverse the parsed config

The List.fold_left creates a dictionary with keys in the reverse order
compared to how they are presented in the config file. Reversing the
dictionary again leads to the order being preserved.

Signed-off-by: John Else <john.else@citrix.com>
Add config.mli

Signed-off-by: John Else <john.else@citrix.com>
Add minimal test executable and build rules

Signed-off-by: John Else <john.else@citrix.com>
checkpoint of tests

Signed-off-by: John Else <john.else@citrix.com>
Add Config.to_string

Signed-off-by: John Else <john.else@citrix.com>
Add test printer

Signed-off-by: John Else <john.else@citrix.com>