add main field to package.json
add support for umd
Merge pull request #39 from CondeNast/main-package-json

add main field to package.json
Merge pull request #41 from CondeNast/umd-support

add support for umd
Test framework and jshint adjustments
We don't even use grunt for testing
Testing constructor.
Testing new Constructor API (tests are obviously failing)
Handling images in fixtures

Conflicts:
	test/unit/core.js
Removing $ from the global namespace to avoid conflicting with the internal dollar and tests

Conflicts:
	test/unit/core.js
Testing new `data-src` syntax.

- initial tests are failing because the old feature is still working (good way to know the old expectation we are going to break)
- new tests are  not working because basically it's not done yet
regex -> {width}

- removed Imager `regex` option
- implemented simple `{width}` interpolation
Pixel ratio tests
Pixel ratio implementation

- added Imager.transforms to let room to customise things further on
- replacing {pixel_ratio} pattern in `data-src` URI
Fixed typo in test label.
Made timeout execution more explicit
`pixel_ratio` -> `pixelRatio` as method name.

Also made the pixel ratio computation executed once, not every time an image is replaced (because it is not supposed to change within the lifecycle of a page).
Codestyle consistency
Testing dynamic size computation
Implementing dynamic size calculation