Opening keyboard on Android messes up section sizes

### Description
When viewing a Fullpage-powered site on an Android device, typing into an input field causes the section sizes to become messed up. It only occurs when you start typing, which drags the input field into view, forcing the page to scroll and break the Fullpage plugin.

Here is an example:


The problem is worsened if the device is in landscape mode. Often the next slide simply becomes fully visible:


Scrolling the page manually afterwards does not remove the effect; the offset created by this issue persists until the page is reloaded. If setAllowScrolling is false, this prevents page transitions all together, as both the original and newly visible sections will scroll but not initiate a page change.

Invoking $.fn.fullpage.reBuild() resolves the issue sometimes, but only when I call it manually from dev tools. Triggering the function on window resize and orientationchange events does not work.

### Link to isolated reproduction with no external CSS / JS
JS Fiddle: https://jsfiddle.net/ho5f6mex/

### Steps to reproduce it
1. Ensure there is a text input on your section.
2. Focus on text input to cause keyboard to appear.
3. Start typing to force the input field into view.
4. Close the keyboard
5. The section should be stuck in a "scrolled up" position, partially showing the following slide.

### Versions
Confirmed on Nexus 5, Nexus 7 and Galaxy S5 devices.