We used to use HorizontalAlignment uno command for cell alignment
both in online and gtktiledviewer. To make things simpler, lets
use separate cell alignment uno commands for spreadsheets like we
have in writer and impres.

Change-Id: I2a959d1892f6b02db7a9ce51d55309216e4b3c6c
Reviewed-on: https://gerrit.libreoffice.org/33444Reviewed-by: pranavk <pranavk@collabora.co.uk>
Tested-by: pranavk <pranavk@collabora.co.uk>