fix(repeat): use 0-based indexing for repeater rows

BREAKING CHANGE: Finding rows with protractor.By.repeater now
indexes from 0 instead of 1. This should be more familiar to most
modern programmers. You will need to edit existing tests. Closes #90.

Before:

// The fourth foo
ptor.findElement(protractor.By.repeater('foo in foos').row(4));

After:

// The fourth foo
ptor.findElement(protractor.By.repeater('foo in foos').row(3));