Fix compiling DTL templates with latest erlydtl

The latest version of erlydtl requires that custom tag modules be in
the path when templates are compiled. Without this change rebar silently
exits when using the custom_tags_modules option.

src/rebar_erlydtl_compiler.erl

@@ -82,12 +82,16 @@
 
 compile(Config, _AppFile) ->
     DtlOpts = erlydtl_opts(Config),
-    rebar_base_compiler:run(Config, [],
-                            option(doc_root, DtlOpts),
-                            option(source_ext, DtlOpts),
-                            option(out_dir, DtlOpts),
-                            option(module_ext, DtlOpts) ++ ".beam",
-                            fun compile_dtl/3, [{check_last_mod, false}]).
+    OrigPath = code:get_path(),
+    true = code:add_path(filename:join(rebar_utils:get_cwd(), "ebin")),
+    Result = rebar_base_compiler:run(Config, [],
+                                     option(doc_root, DtlOpts),
+                                     option(source_ext, DtlOpts),
+                                     option(out_dir, DtlOpts),
+                                     option(module_ext, DtlOpts) ++ ".beam",
+                                     fun compile_dtl/3, [{check_last_mod, false}]),
+    true = code:set_path(OrigPath),
+    Result.
 
 
 %% ===================================================================