Fix #89, images not loaded when revealed by resize

The problem was twofold:
1. scrollCheck did nothing, because the value of scrolled was left false.
2. Even so, The viewportHeight is set at first load and not changed, so isThisElementOnScreen would still fail if the element was below the original viewport.
Karma 0.12, simplified test command and more browser definitions.
Sequenced Travis tests.
Faster Browserstack CI.
Browserstack secured credentials.
Quick fix due to BrowserStack 'dot in path' bug
Build matrix.
Merge pull request #103 from BBC-News/karma-012

CI move to BrowserStack
v0.3.0
Merge branch 'master' of github.com:paul-butcher/Imager.js into paul-butcher-master

* 'master' of github.com:paul-butcher/Imager.js:
  Fix #89, images not loaded when revealed by resize
Add test.
Merge branch 'paul-butcher-master'

* paul-butcher-master:
  Add test.
  Fix #89, images not loaded when revealed by resize
Lazyload demo fix.

Starting at 320 and increasing the size of the window reveals that lazyloaded images do not scale up if necessary.

refs #71
`this.divs` does not get damaged anymore with lazyloaded images replacement.

Although now a resize event resize placeholder images as well.
This is going to be fixed in the next commit.
Replace only non-placeholder images on resize + lazyload.
Remove default width for Grunt demo
JSHint compliance.
Allow IE7 failure for the moment.
Merge pull request #104 from BBC-News/fix-71

Lazyload updates only response images on resize
iOS6 -> iOS6.1 for BrowserStack config.