AndroidStudio:Gradlesync失败:Project:app声明了依赖项

我在Android Studio 2.3中工作,我想使用我在github上找到的库(https://github.com/henrychuangtw/Android-ChatHead)并且没有Jar文件.在settings.gradle中,我已经声明了库所在的目录,如下所示:

include ':app'
include ':Android-ChatHead'

project(':Android-ChatHead').projectDir=new File('/Users/lorand/AndroidStudioProjects/Doritest/android_chatHeads')

我还将库添加到build.gradle依赖项中:

dependencies {

        compile fileTree(dir: 'libs', include: ['*.jar'])

        compile project(':Android-ChatHead')

        androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
            exclude group: 'com.android.support', module: 'support-annotations'
        })
        compile 'com.android.support:appcompat-v7:25.1.1'
        compile 'com.android.support.constraint:constraint-layout:1.0.2'
        testCompile 'junit:junit:4.12'
    }

在此之后,如果我同步,我会收到此错误:

Gradle sync失败:Project:app声明从配置'compile'到配置'default'的依赖关系,它未在项目描述符中声明:Android-ChatHead.有关更多详细信息,请参阅IDE日志(帮助|显示日志)

如果我将/ app添加到settings.gradle文件路径的末尾,则会出现以下错误:

Error:Dependency Doritest:Android-ChatHead:unspecified on project core resolves to an APK archive which is not supported as a compilation dependency. 
File: /Users/lorand/AndroidStudioProjects/Doritest/android_chatHeads/Android-ChatHead/app/build/outputs/apk/Android-ChatHead-release-unsigned.apk

我无法弄清楚我应该做些什么.