Add $mdTheming service to angular-material

[mtraynham]

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• Use a meaningful title for the pull request. Include the name of the package modified.
• Test the change in your own code. (Compile and run.)
• Follow the advice from the readme.
• Avoid common mistakes.
• Run npm run lint package-name (or tsc if no tslint.json is present).

Select one of these and delete the others:

If changing an existing definition:

• Provide a URL to documentation or source code which provides context for the suggested changes:
  https://material.angularjs.org/latest/api/service/$mdTheming
  $mdThemingProvider - registering a theme on the fly angular/material#2965
• Increase the version number in the header if appropriate.
• If you are making substantial changes, consider adding a tslint.json containing { "extends": "dtslint/dt.json" }.

[dt-bot]

types/angular-material/index.d.ts

to authors (@blbigelow @PeterHajdu @Dona278 @geertjansen). Could you review this PR?
👍 or 👎?

[mtraynham]

Testing angular-material
	Running: node /home/travis/build/DefinitelyTyped/DefinitelyTyped/node_modules/dtslint/bin/index.js
	Error: /home/travis/build/DefinitelyTyped/DefinitelyTyped/types/angular-material/index.d.ts
ERROR: 7:26 no-implicit-dependencies Module 'angular' is not listed as dependency in package.json

Not entirely sure why that failed. The index file already imports angular. Is the import broken here?

[ghost]

@mtrayham Sorry, this looks like a new lint rule. I'll disable it since we use path mapping on DT. (palantir/tslint#3364)

[mtraynham]

No worries @andy-ms. Thanks for help!

[geertjansen]

LGTM

[typescript-bot]

Approved by a listed owner. PR ready to merge pending express review by a maintainer.