Remove some hardcoded paths from atom.spec.in

Also, fix a couple lines in atom.spec.in that either weren't
really doing anything or were inconsistent with the rest of the
script.

script/mkrpm

@@ -11,7 +11,7 @@ ARCH=`uname -m`
 
 rpmdev-setuptree
 
-cp -r $BUILD_DIRECTORY/Atom/* $RPM_BUILD_ROOT/BUILD
+cp -r $BUILD_DIRECTORY/Atom $RPM_BUILD_ROOT/BUILD
 cp $SPEC_FILE $RPM_BUILD_ROOT/SPECS
 cp ./atom.sh $RPM_BUILD_ROOT/BUILD
 cp $DESKTOP_FILE $RPM_BUILD_ROOT/BUILD