Fix dump command

[gabor-boros]

Reason for the change
#137

Description
As it turned out, all the commands receiving the parameters like sys.argv[1:] except the dump command. Because of this, the command ignored the first parameter which is usually the --connect so the users were not able to connect to their RethinkDB servers.

Note
This PR also contains some adjustments for pytest's config. The Unit/integration tests are missing right now for all the commands, but we will need to include them later.

Code examples
Run the script as a python script
python -m rethinkdb dump -c localhost:28015

Run the script as an installed script
rethinkdb-dump -c localhost:28015

References
Related issues in the past:

• rethinkdb dump failing #104

[alexa-infra]

@gabor-boros it seems to be a clean solution for rethinkd-dump bug #137. I have tested briefly rethinkdb-dump <args> and python -m rethinkdb dump <args> command invocations with your changes and they don't skip the first parameter now. import/export and other commands seem to be good too.

IMO command line parser needs a general refactoring: optparse is deprecated and has to be replaced by argparse, some argument help-texts are missing/outdated, etc.

[gabor-boros]

I totally agree with you to replace optparse but did now wanted to include that change here. I’ll merge this PR and create a post release to resolve the issue.

In the future we will need tests for these scripts and also we need to replace optparse