fix erlydtl 0.8 compilation

Currently erlydtl 0.8+ compilation is broken and raises the following errors:

    unexpected error compiling templates/profile.html
    {'EXIT',{{case_clause,{ok,profile_dtl}},
             [{rebar_erlydtl_compiler,do_compile,4,
                                      [{file,"src/rebar_erlydtl_compiler.erl"},
                                       {line,208}]},
              {rebar_base_compiler,compile,3,
                                   [{file,"src/rebar_base_compiler.erl"},
                                    {line,121}]},
              {rebar_base_compiler,compile_worker,3,
                                   [{file,"src/rebar_base_compiler.erl"},
                                    {line,194}]}]}}
    ERROR: compile failed while processing /Users/dialtone/dev/Adroll/dyno: rebar_abort
    make: *** [all] Error 1

With this simple pull request you can compile erlydtl templates again.