Add tests for call expressions, with spaces, tabs and nested custom indent

This should help with #141, since it highlights several problems that the current testsuite don't cover.

First, the chained call expression isn't indented at all if its on the right side of an AssignmentExpression.

Second, custom indent like the one used here to format the long string broken up on two lines is thrown away, but should be kept - or at least it should be possible to configure esformatter to keep this extra indent.