Fix bug in upgrading rpm

Because of changing filenames, upgrading the package was broken. It
appears to be that the scripts are run in the order of:
 1. postinstall of new
 2. preuninstall of old
 3. postuninstall of old

buildconfig/CMake/Packaging/rpm/scripts/rpm_post_install.sh.in

@@ -21,10 +21,13 @@ if [ ${ENVVARS_ON_INSTALL} -eq 1 ]; then
     ln -s $RPM_INSTALL_PREFIX0/@ETC_DIR@/mantid.csh /etc/profile.d/mantid.csh
     ln -s $RPM_INSTALL_PREFIX0/@ETC_DIR@/mantid.pth @PYTHON_SITE@/mantid.pth
 else
-    # Create symbolic links in world's path
-    if [ ! -L /usr/bin/mantidplot@CPACK_PACKAGE_SUFFIX@ ]; then
-        ln -s $RPM_INSTALL_PREFIX0/@BIN_DIR@/mantidplot /usr/bin/mantidplot@CPACK_PACKAGE_SUFFIX@
+    # symbolic links in world's path of mantidplot
+    if [ -f $RPM_INSTALL_PREFIX0/@BIN_DIR@/mantidplot ]; then
+      if [ ! -L /usr/bin/mantidplot@CPACK_PACKAGE_SUFFIX@ ]; then
+          ln -s $RPM_INSTALL_PREFIX0/@BIN_DIR@/mantidplot /usr/bin/mantidplot@CPACK_PACKAGE_SUFFIX@
+      fi
     fi
+    # symbolic link for mantidpython
     if [ ! -L /usr/bin/mantidpython@CPACK_PACKAGE_SUFFIX@ ]; then
         ln -s $RPM_INSTALL_PREFIX0/@BIN_DIR@/mantidpython /usr/bin/mantidpython@CPACK_PACKAGE_SUFFIX@
     fi

buildconfig/CMake/Packaging/rpm/scripts/rpm_post_uninstall.sh.in

@@ -10,7 +10,7 @@ ENVVARS_ON_INSTALL=@ENVVARS_ON_INSTALL_INT@
 # Remove exe and links only if it looks like we were removed
 # and not upgraded. If launch_mantidplot.sh exists then package
 # has been upgraded and MantidPlot_exe replaced so don't touch anything
-if [ ! -e $RPM_INSTALL_PREFIX0/@BIN_DIR@/launch_mantidplot.sh  ]; then
+if [ ! -e $RPM_INSTALL_PREFIX0/@BIN_DIR@/mantidplot ]; then
     rm $RPM_INSTALL_PREFIX0/@BIN_DIR@/MantidPlot_exe
 
     if [ ${ENVVARS_ON_INSTALL} -eq 1 ]; then