update changelog to 10.2.0

Change-Id: I9d752da789e6b47216fd264bc4ef62c95e105b0d
add contributors for samsung exhilarate

Change-Id: Idc31a88b73db2030c8712f8f90b90e1360aee2df
Merge "add contributors for samsung exhilarate" into cm-10.2
contributors: update version to 10.2

Change-Id: I8ce35eb3a282ca84467b0ca210aaf29fe2042c0e
Merge branch 'cm-10.2' of git://github.com/CyanogenMod/android_vendor_cm into cm-10.2