setup siesta testing suite

[themightychris]

• [x] setup basic siesta sanity test to verify framework is loaded
• [ ] create series of tests that check that rowsStore and columnsStore return correct counts and the update event has been fired exactly once with every combination of instantiation, store configuration, and rendering happeing in different orders and groupings

[aliyeysides]

I have the checks against instantiation and store configuration but not sure if I understand that last 'rendering' part. I have a check for component visibility which fires after render but idt that's what you wanted

[themightychris]

@aliyeysides in the current test, renderTo: Ext.getBody() is provided to Ext.create, meaning the component is rendered immediately during instantiation and doesn't have to go through a state of being created but not yet rendered. Create tests where it is created without renderTo, and then call aggregrid.setRenderTo(Ext.getBody()) later

[themightychris]

@aliyeysides additionally I left you a bunch of comments on the code in #93