在build.gradle中引用 butterknife库时，报出如下错误：
错误表现：FAILURE: Build failed with an exception.
* What went wrong:
Execution failed for task ':app:transformClassesWithInstantRunForDebug'.
错误原因：这可能是由于butterknife中依赖的v4包引起的
修改前：
exclude group: 'com.android.support'
修改后：
compile('com.jakewharton:butterknife:8.8.1') {
exclude group: 'com.android.support'
}