[Android] Implement Oreo notification channels

[Geoffrey Métais]

vlc-android | branch: master | Geoffrey Métais <geoffrey.metais at gmail.com> | Tue Aug 22 14:52:35 2017 +0200| [bdc6004f31b9063a584c0a22971de7c10fe45e10] | committer: Geoffrey Métais

Implement Oreo notification channels

> https://code.videolan.org/videolan/vlc-android/commit/bdc6004f31b9063a584c0a22971de7c10fe45e10
---

 .../src/org/videolan/vlc/MediaParsingService.java  |  30 +---
 .../src/org/videolan/vlc/PlaybackService.java      |  68 ++------
 .../vlc/gui/helpers/NotificationHelper.java        | 185 +++++++++++++++++++++
 vlc-android/src/org/videolan/vlc/util/Util.java    |  13 +-
 4 files changed, 214 insertions(+), 82 deletions(-)

Diff:   https://code.videolan.org/videolan/vlc-android/commit/bdc6004f31b9063a584c0a22971de7c10fe45e10