Add a feature to stay at maxZoom instead of resetting to initialZoom

[ajayg415]

This PR includes a new optional Boolean parameter stayAtMaxZoom, that will conditionally return the next zoom step when user reached maximum zoom value.

Scenario1:

• user did not set this value in local.
• so framework will pick default value false
• user reached maximum zoom value and made double clicks.
• view is reset to initialZoom value

Scenario 2:

• user set stayAtMaxZoom = true in his local.
• user reached maximum zoom value and made double clicks.
• view won't get is reset to initialZoom instead stays at maximumZoom value.

I'm not sure how much this feature is useful to others, I need this requirement in my application. so I raised one feature request ( #80) and this PR simultaneously.