bnc#885825: Support borders around data labels.

Change-Id: Ib141413e523cbf73746876f727e9f80dda9f5f7c
bnc#885825: OOXML import and export of data label borders.
bnc#885825: Handle ODF import and export of data label border properties.

Change-Id: Ic8c7bc873768008537cd52a3fd4b11031b403139