Fix for IE7 spec failure when run against knockout-raw.js

For some reason, on IE7 json2.js is treated as not yet loaded when
knockout-raw.js first starts running, even though its script tag is
higher up in the page. So it doesn’t work to capture a reference to it
in the test. However this doesn’t affect production builds.
Fix specs that failed due to IE<8 not supporting x[i] to retrieve chars from strings
Extend fix from #1208 to all browsers since Firefox also has a problem with selection when deleting options first.
Bump version to 3.1.0beta
In spec runner, load Jasmine before jQuery, otherwise the clock mocking breaks on IE 8 and below
Merge pull request #1309 from knockout/v3.1-fix-spec-failures

V3.1 fix spec failures