Added merge button
Added checkbox in the table to enable Activity Selection before merging
Added code to enable the merge button only when make sense
Merge pull request #105 from SmokyBob/feature/material_design

Implementation of Issue #103 + gde_name field left empty on save of a new activity as the API will calculate it anyway
Text fixes
Proper English for as in #95
Merge remote-tracking branch 'maiera/feature/material_design' into feature/material_design