Update Changelog

Initial pass at updating the changelog, as this hasn't been
done for a few releases. Feel free to add anything I left out, as well
as device specific tweaks and customizations. Also, I have left off
contributor names, but you can add yourself or others where appropriate.

Patchset #2: Remove Extra Space

Change-Id: I1158e8063870e01c67dc09c23f79869863edd08c
Update README for CM 10.1

Update to reflect:

1) CM .org changes
2) Fix 404 for Repo help and add in git help page
3) Point to cm-10.1 branch
4) Fix reference to buildbots to point to Jenkins instead

Patchset 2: White space, missed a .org and fixed grammar for Jenkins.
Patchset 3: Fix wiki link 404 due to short-url extension. Swap a few urls to https

Change-Id: I89510d6afcab0e1c302dd31884eeb130e9324142
Merge branch 'cm-10.1' of https://github.com/CyanogenMod/android_vendor_cm into cm-10.1