Enable time button
Not displaying dummy timestamp for lubis layers.

For LUBIS layer we use a 'dummy' timestamp to display all available
year. As this timestamp has not real meaning, it must not be displayed.
Adapt tooltips for LUBIS layer.

WMTS layer with timestamp well above the current year have a special
meaning and should not be queried as it were normal timestamp.
Merge pull request #1271 from geoadmin/lubis_demo

Lubis branch