Revert ot tycho 0.20 as I am unable to build some tests with 0.21
Revert ot tycho 0.20 as I am unable to build some tests with 0.21

sazgin/elexis-3-core,sazgin/elexis-3-core,sazgin/elexis-3-core,sazgin/elexis-3-core,elexis/elexis-3-core,elexis/elexis-3-core,elexis/elexis-3-core,elexis/elexis-3-core