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.

resources/linux/redhat/atom.spec.in

@@ -12,13 +12,13 @@ Prefix:         /usr/local
 
 %install
 mkdir -p %{buildroot}/usr/local/share/atom
-cp -r /tmp/atom-build/Atom/* %{buildroot}/usr/local/share/atom
+cp -r Atom/* %{buildroot}/usr/local/share/atom
 mkdir -p %{buildroot}/usr/local/bin/
 ln -sf ../share/atom/resources/app/apm/node_modules/.bin/apm %{buildroot}/usr/local/bin/apm
 cp atom.sh %{buildroot}/usr/local/bin/atom
-chmod 755 atom.sh
+chmod 755 %{buildroot}/usr/local/bin/atom
 mkdir -p %{buildroot}/usr/local/share/applications/
-mv atom.desktop %{buildroot}/usr/local/share/applications/
+cp atom.desktop %{buildroot}/usr/local/share/applications/
 
 %files
 /usr/local/bin/atom