[Feature] Add BINTRAY_USER to fix CI.

Author: zhanghai

gradle.properties

@@ -27,6 +27,7 @@ POM_SCM_CONNECTION=scm:git@github.com:zhanghai/AndroidFastScroll.git
 POM_SCM_DEVELOPER_CONNECTION=scm:git@github.com:zhanghai/AndroidFastScroll.git
 POM_SCM_URL=https://github.com/zhanghai/AndroidFastScroll
 
+BINTRAY_USER=zhanghai
 BINTRAY_REPO=AndroidFastScroll
 BINTRAY_ISSUE_TRACKER_URL=https://github.com/zhanghai/AndroidFastScroll/issues
 BINTRAY_VCS_URL=https://github.com/zhanghai/AndroidFastScroll