Don't use POST method for sql_select/explain

[pgiraud]

I've installed the debug toolbar on my application and it works well. Thanks.

But because I was using Flask_WTF with CSRF protection, I was receiving 400 Bad Request errors each time I was clicking on the SELECT or EXPLAIN link in the SQLAlchemy panel.
Of course, I found a proper way to handle this with better configuration of the CSRF protection in my app.

However I don't think that we need to use the POST method for the sql_select or sql_explain routes.

This pull request makes sure that we only accept GET and that the browser uses the correct method to call the service (using JQuery load method).

[caffeinatedMike]

@pgiraud While I also face this issue with the SQLAlchemy query panel, using GET is not the best approach seeing as complicated queries can easily surpass the url length limit. See #156 for how we can fix the issue.

[jeffwidman]

Thanks for swinging by @caffeinatedMike. I totally forgot about the url length limit! Good call.

Always happy to review a PR if you want to suggest an alternative approach. 😄

[caffeinatedMike]

@jeffwidman the approach suggested in #156 is the way to go. Sorry I haven't been able to carve out any time to create a PR for it.

[macnewbold]

I know it's been a little while, but do you still have any interest in this?
If so, it will need to catch it up with master and retest. If not, we'll probably close it out.