Provide progress bar when importing WxS GetCapabilities document

[palmerj]

At the moment the QGIS UI locked up for over 2 minutes when the API key is saved or the plugin UI is started for the first time in a new QGIS session. This is because loading the LDS WxS capability documents is slow

It would be good to add some type of non-blocking progress bar when loading the WxS capability documents.

[palmerj]

My last import took 5mins!

[SPlanzer]

My last import took 5mins!

Wow. Yeah that is not going to work.

[SPlanzer]

#9 has made the loading of documents much faster. The only time the loading is slow is the first time the plugin is ever ran. I am hoping the users can tolerate one slow load and then the plugin handles all future document getting in the background.

Feedback will be gathered via #26

[stale]

This issue has been automatically marked as stale as there has not been any activity for sometime. The issue will be closed in 5 days if no further activity.

[SPlanzer]

The first time a service is added in the settings the plugin can become un-responsive. There is a label indicating this. There after due to caching there are no un-responsive issues.

I do not see this as required