Migrates eslint-plugin to typescript.
There's a big refactor in here to make creating a rule easier / more standardised.

• Types are a lot stricter:
  • Rule metamust usemessageId.
  • Rule metamust includedocs.
    • Docsmust includecategory,description, andrecommended.
• Reduced boilerplate:
  • Automatically addsurl to the meta.
  • Automatically merges default options for a rule
  • OnceImplement partial type argument inference using the _ sigil microsoft/TypeScript#26349 is merged, the generic typing will only require theTOptions type.
    • Maybe we can look at auto-generating the JSONSchema in future based on the interface type?

Build is passing across the board.

• Note that the packages will now include.js.map and.d.ts.map files.

Tests have been largely untouched apart from the rename, and they are all passing.

closes#47
closes#40

Waiting for the following PRs to be merged in to master:
#178,#192,#204,#215,#231

Closed waiting PRs
#155,#194,#199,#206,#222,#226,#232