Drop older versions of erlang, not supported by travis.
Drop older versions of erlang, not supported by travis.

truqu/erlydtl,campanja-forks/erlydtl,truqu/erlydtl,erlydtl/erlydtl,chaptastic/erlydtl,quasiconvex/erlydtl,campanja-forks/erlydtl,quasiconvex/erlydtl,wrw/erlydtl,A40in/erlydtl,alexr/erlydtl,alexr/erlydtl,aerosol/erlydtl,project-fifo/erlydtl,wrw/erlydtl,huangered/erlydtl,aerosol/erlydtl,wrw/erlydtl,oxpa/erlydtl,project-fifo/erlydtl,alexr/erlydtl,huangered/erlydtl,erlydtl/erlydtl,project-fifo/erlydtl,aerosol/erlydtl,quasiconvex/erlydtl,A40in/erlydtl,A40in/erlydtl,oxpa/erlydtl,oxpa/erlydtl,huangered/erlydtl,erlydtl/erlydtl,kivra/erlydtl,kivra/erlydtl,kivra/erlydtl,truqu/erlydtl,campanja-forks/erlydtl,chaptastic/erlydtl,chaptastic/erlydtl