chore: rename karma.conf to default karma.conf.js

So that one can start karma just by `karma start` without specifying the config file.
test: add toHaveClass() matcher
feat: add ng-class directive

Very basic implementation, that only allows expression to be a string (can contain either a single class or multiple classes separated by coma).
feat: add ng-show, ng-hide directives
style: reorder directives by alphabet
feat: add ng-if directive

This is very initial version, that only removes the element (block) from the DOM. It does not detach the scope and therefore it is still digested.

Misko is changing this completely (removing atach/detach API), so I will implement this once Misko is done.
chore(directives): Disabled a failing test
tests(interface_typing): Added a test for mixins and mirrors
fix(parser): Do not use isInterface.  Works around dartbug 9434
chore(tests): Remove an iit
WIP: removed BlockCache

Conflicts:
	lib/angular.dart
	lib/block.dart
	lib/block_list.dart
	lib/block_type.dart
	test/compiler_spec.dart
chore(tests): clean up modules in tests
chore(demo): update to work with latest
fix(ngClass): update if value set before first digest
feat(compiler): support $publishAs on components.
chore(tests): re-enable all tests
Replaced questionmark operator throughout
Merge pull request #23 from pavelgj/remove-questionmarks

Replaced questionmark operator throughout as it's deprecated