Fix example for table and config

[prateeknischal]

When running an extension with osqueryi or osqueryd, osquery* binary spawns the extension process with the following command line args

--socket /path/to/socket --timeout 3 --interval 3

The example plugins only accept 2 arguments for a valid invocation which caused the extension to fail when running via --extension flag.

Fix by adding a more formal flag parsing.

Usage:

1. When running the extension as a self managed process:

   osqueryi

   and then

   ./extension.ext --socket /var/osquery/osquery.em

2. Allowing osquery extension manager to manage the lifecyle of the extension

   osqueryi --extension extension.ext

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