Rule: max-statements

Created `max-statements` rule, which allows you to specify the maximum number of statement in a function. Statements in inner functions do not count toward the statement count of the outer function.

```js
// max-statements: [1, 2]  // Maximum of 2 statements.
function foo() {
  var bar = 1;
  var baz = 2;

  var qux = 3; // Too many.
}
```

This rule matches JSHint's **maxstatements** rule.
Documentation for no-delete-var rule. Closes #129
Corrected file extension on no-plusplus rule documentation.
Merge pull request #127 from iancmyers/rule-maxstatement

Rule: maxstatements
Merge pull request #130 from ilyavolodin/no-delete-var

Documentation for no-delete-var rule. Closes #129
Merge pull request #131 from iancmyers/fix-file-name

Corrected file extension on no-plusplus rule documentation.