CASJobs Integration

[umesh-timalsina]

Now that #1309 and #1299 are resolved with few bugs and bugfixes. It would be nice to integrate CasJobs query api from SDSS.

[umesh-timalsina]

As, pointed out before by @brollb, this integration will be helpful to deploy an end to end pipeline without having to worry about intermediate data representation or broken chain in a Pipeline

[umesh-timalsina]

Here's an action plan for this implementation:

• Ensure you are familiar with CASJobs queries
• Survey existing visual languages/editors for SQL
• Mock up an example (or a couple different approaches) and either message me or post it on the issue tracker. The goal is to find any shortcomings or issues before writing code
  Determine where deepforge's extension API needs to be extended, if necessary.
• Create a deepforge-casjobs repo and implement the visualizer, code generator, and create the metamodel

[brollb]

This might actually be a good candidate for an interactive editor.