Status bar clock and date customization (1/2)

Thanks SlimRoms for this codes.
Based on this commit: https://github.com/SlimRoms/frameworks_base/commit/39545c535c0d0d6857dd769eeae8bda73955d3b1

Change-Id: Ib13e7fd18ae2f22c12eedb8adbae0127822faa6e

Conflicts:
	packages/SystemUI/res/layout/status_bar_expanded_header.xml