Attempt to make easier the creation of unit tests that check the drawing output. Until now, this was done by checking calls on a 'fake' context, which is hard to maintain (need to update pixel values by hands) and also not reliable when optimizing code (i.e. different calls sequence but same result).
As of now, it's possible to define 'auto' tests based on JSON/PNG fixtures: chart is generated from the JSON file and compared to the associated PNG image. The image diff is done using `pixelmatch`. As an example (and in preparation of the `filler` plugin), add auto tests for the line element `fill` options.
`karma.conf.ci.js` has been merged into `karma.conf.js` for local testing consistency: `gulp unittestWatch` has been replaced by `gulp unittest --watch` and thus use exactly the same config file. Upgrade to latest jasmine and karma packages and remove deprecated `gulp-karma` dependency (directly use `karma.Server` in gulp).
Split `test/mockContext.js` into smaller `test/jasmine.*` modules to make easier unit tests maintenance and finally, move all `*.test.js` files under the `test/specs` folder.
If a value is set on the model after `pivot()` has been called, the view wasn't initialized and the animation started from 0. Now, `_start` and incomplete `_view` are initialized to the model value during the transition (no initial implicit transition).
Also remove exception handling when animating a string (color), which is faster when string are not valid colors (e.g. tooltip position). It requires to update `chartjs-color` to version 2.1.0.
Add the --inputs command switch to the unittest and unittestWatch tasks, to be able to run unit tests from the specified files only (e.g. gulp unittest --inputs=test/core.element.tests.js;test/core.helpers.tests.js).
Change the linter in gulp tasks to be consistent with Code Climate results which are based on ESLint using .eslintrc options. However, defaults Code Climate rules are too strict, so turn as warnings the 'complexity' and 'max-statements' rules (other errors has been fixed). Note that the Gulp task name has been changed for `gulp lint`.
Samples need to be packaged with built libraries (which one have been removed from the repository), so create a new `gulp package` task to generate a ZIP archive with dist files, samples and the license file. This archive is generated in the ./dist/ folder and will be deployed by Travis along the GH release. Note that the ./dist/ folder is not preserved but merged in the archive root. Also change samples requiring moment.js to load this lib from the CDN instead of the ./node_module folder.
Fix color animation because the color lib changed the `mix` implementation to match SASS behavior, so the weight specifies the amount of the first color that should be included in the returned color.
