Remove support for Fedora 21 (EOL); add F22 where appropriate

Fedora 21 reached its End Of Life (EOL) on 1-DEC-2015[1]; remove it as
supported distribution.

    - stack.sh: Remove Fedora 21 from list of supported distributions.
    - tools/fixup_stuff.sh: Make the minimum Fedora version to be F22 in
      from a conditional check in 'Python packages' section
    - files/rpms/general: Remove 'f21' from NOPRIME.
    - lib/ceph: Remove 'f21' from the check_os_support_ceph() function.
    - doc/source/index.rst: s/Fedora 21/Fedora 22/
    - pkg/elasticsearch.sh: Remove the 'if' conditional in the
      install_elasticsearch() function.

[1] https://fedoramagazine.org/fedora-21-end-life-december-1st/

Change-Id: Ifbcc3dd783ff2f362a464fbf4ca22f20cc2c658e
diff --git a/tools/fixup_stuff.sh b/tools/fixup_stuff.sh
index 9ae2ae7..193a1f7 100755
--- a/tools/fixup_stuff.sh
+++ b/tools/fixup_stuff.sh
@@ -135,7 +135,7 @@
         fi
     fi
 
-    if  [[ "$os_VENDOR" == "Fedora" ]] && [[ "$os_RELEASE" -ge "21" ]]; then
+    if  [[ "$os_VENDOR" == "Fedora" ]] && [[ "$os_RELEASE" -ge "22" ]]; then
         # requests ships vendored version of chardet/urllib3, but on
         # fedora these are symlinked back to the primary versions to
         # avoid duplication of code on disk.  This is fine when