Use lowercase hashed directories

On case-insensitive filesystems it is not such a good idea to have
directories that only differ in case. Packages should be always split
into lowercased directories.

The test data is modified to include some packages starting with
uppercase letters. The example in code can be verified by running
`nosetests --with-doctest`.

Signed-off-by: Lubomír Sedlář <lsedlar@redhat.com>

tests/data/dummy-comps.xml

@@ -45,7 +45,7 @@
     <default>false</default>
     <uservisible>false</uservisible>
     <packagelist>
-      <packagereq>dummy-firefox</packagereq>
+      <packagereq>Dummy-firefox</packagereq>
       <packagereq>dummy-icedtea-web</packagereq>
     </packagelist>
   </group>

tests/data/specs/Dummy-firefox.spec

@@ -1,11 +1,11 @@
-Name:           dummy-firefox
+Name:           Dummy-firefox
 Version:        16.0.1
 Release:        1
 License:        LGPLv2
 Summary:        A dummy firefox package
 BuildRequires:  dummy-krb5-devel
-BuildRequires:  dummy-xulrunner
-Requires:       dummy-xulrunner
+BuildRequires:  Dummy-xulrunner
+Requires:       Dummy-xulrunner
 
 %description
 A dummy firefox package

tests/data/specs/Dummy-xulrunner.spec

@@ -1,4 +1,4 @@
-Name:           dummy-xulrunner
+Name:           Dummy-xulrunner
 Version:        16.0.1
 Release:        1
 License:        LGPLv2