…gle line (typescript-eslint#203)

This PR adds better handling for single line delimiters, and better enforces the `requrieLast` option.

Fixes typescript-eslint#92

## Single line delimiters

Previously single line delimiters were either checked or not. This meant that if you used
```
{
    delimiter: "none",
    ignoreSingleLine: false,
}
```
then the fixer would break your code by removing the delimiter from single line statements i.e.:
```TS
interface Foo { bar: string, baz: number }
// fixed to this broken line
interface Foo { bar: string baz: number }
```

### Breaking change:
- Removed option `ignoreSingleLine`
- Added option `singleLine: "none" | "semi" | "comma"`

`singleLine` works the same as `delimiter`, except for single line statements only.

## Stricter `requireLast`

Previously `requireLast` did nothing when turned off, and enforced having a delimiter when turned on.

I felt this was inconsistent with the goals of the linter; being a tool to provide consistent coding conventions.

This is the first of two changes to bring the option into line with eslint's [`comma-dangle`](https://eslint.org/docs/rules/comma-dangle#options). (The next change will replace the boolean with an enum; I didn't want to overload this PR).

### Breaking change:
- `requireLast: false` now enforces that there is no delimiter on the last member.