optional_args are not forwarded correctly from CLI tools

[kderynski]

I have noticed that there is an issue with optional_args forwarded from CLI based tools (cl_napalm_test and cl_napalm_configure). I have checked it against junos driver with fresh install of napalm version 0.23.0 (tested on macOS and ubuntu 16.04). All values from optional_args are forwarded from CLI as unicode and they are used directly in drivers. It causes an issue in case of basic port parameter. Drivers (junos and arista at least) are expecting integers, so variables should be casted in CLI tools code or in drivers code.

Example use of cli based tool:

cl_napalm_configure --user root --password Juniper --vendor junos --optional_args 'port=22' --strategy merge 192.168.50.6 merge_test.txt

and exception for this example:

Traceback (most recent call last):
  File "/usr/local/bin/cl_napalm_configure", line 9, in 
    load_entry_point('napalm-base==0.23.0', 'console_scripts', 'cl_napalm_configure')()
  File "/usr/local/lib/python2.7/dist-packages/napalm_base/clitools/cl_napalm_configure.py", line 59, in main
    args.optional_args, args.config_file, args.dry_run))
  File "/usr/local/lib/python2.7/dist-packages/napalm_base/clitools/cl_napalm_configure.py", line 32, in run
    with driver(hostname, user, password, optional_args=optional_args) as device:
  File "/usr/local/lib/python2.7/dist-packages/napalm_base/base.py", line 54, in __enter__
    self.__raise_clean_exception(exc_info[0], exc_info[1], exc_info[2])
  File "/usr/local/lib/python2.7/dist-packages/napalm_base/base.py", line 82, in __raise_clean_exception
    raise exc_value
jnpr.junos.exception.ConnectError: ConnectError(host: 192.168.50.6, msg: getaddrinfo() argument 2 must be integer or string)

I am happy to fix this issue but I would like to discuss first where it should be fixed, CLI tools (probably the best way imho) or in drivers.