Add support to detect mshtml build

Some IE vulns are build-specific, in that case we need a way to detect the build version. On IE9 and newer, the build version is the same as the one you see in WinDBG when you do lmv m mshtml (or when you right click mshtml.dll, see Product version/File version). On IE8, it returns something else I don't know.

### Verification ###

- [x] Prepare an IE 9 or IE10 box
- [x] Right click C:\Windows\System32\mshtml.dll, check the build version (specifically the last 5 digits, for example: 10.0.9200.16843, note 16843.) This also should be the same thing when you use ```lmv m mshtml``` in WinDBG.
- [x] Use this test case: https://gist.github.com/wchen-r7/3e155cd3c1309d0fc2cc
- [x] In the test case, modify the ```mshtml_build``` requirement
- [x] Make sure that if IE has the right build, BES should return the "exploit".
- [x] Make sure that if IE doesn't have the right build, BES should return a fake 404.