The present invention relates to a compound according to formula I wherein R1 is selected from the group consisting of hydrogen and fluoro and R2 is selected from C1-C4 alkyl and hydrates or solvates thereof. The invention further relates to intermediates for the preparation of said compounds, to said compounds for use in therapy, to pharmaceutical compositions comprising said compounds, to methods of treating diseases with said compounds, and to the use of said compounds in the manufacture of medicaments.