Travis: Fix nexus authentication info accessible via gradle property
Travis: Fix nexus authentication info accessible via gradle property

Please refer to following link for details:
- https://github.com/ReactiveX/RxJava/issues/2586
- https://docs.gradle.org/current/userguide/userguide_single.html#sec:gradle_properties_and_system_properties

What did:
- Re-generate secure key, by modifying property name from NEXUS_USERNAME,
  NEXUS_PASSWORD to ORG_GRADLE_PROJECT_NEXUS_USERNAME,
  ORG_PROJECT_NEXUS_PASSWORD.

Signed-off-by: Taeho Kim <39bb8a82a78ec439edb1474bb941d524bc8990f3@gmail.com>

kunny/android-CircleRefreshLayout,kunny/android-CircleRefreshLayout