rinoh: fix --format handling (issue #284)

The argument needs to be compared case-insensitive

src/rinoh/__main__.py

@@ -91,8 +91,7 @@ def get_distribution_name(dist):
 
 
 def get_reader_by_name(format_name):
-    for entry_point, _ in find_entry_points('rinoh.frontends',
-                                            format_name.lower()):
+    for entry_point, _ in find_entry_points('rinoh.frontends', format_name):
         return entry_point.name, entry_point.load()
     raise SystemExit("Unknown format '{}'. Run `{} --list-formats` to "
                      "find out which formats are supported."

src/rinoh/resource.py

@@ -109,7 +109,8 @@ def find_entry_points(group, name=None):
     """
     yield from ((ep, dist) for dist in ilm.distributions()
                 for ep in dist.entry_points
-                if ep.group == group and (name is None or ep.name == name))
+                if ep.group == group and (name is None
+                                          or ep.name.lower() == name.lower()))
 
 
 # dynamic entry point creation