Document Nimrod commits and fix 'already installed' condition

toolset/setup/linux/frameworks/jester.sh

@@ -5,4 +5,5 @@ RETCODE=$(fw_exists jester)
 
 git clone git://github.com/dom96/jester.git jester
 cd jester
+# most recent commit in branch new-async as of 2014-10-31
 git checkout 3e77ce753293b523004dfdaebd2fb195217f30f0

toolset/setup/linux/frameworks/nawak.sh

@@ -5,6 +5,7 @@ RETCODE=$(fw_exists nawak)
 
 git clone git://github.com/idlewan/nawak.git nawak
 cd nawak
+# version 0.3.0 (2014-11-02)
 git checkout b34b0b5077541ae9671957452a70e2578894d3a8
 
 nimble update

toolset/setup/linux/languages/nimrod.sh

@@ -1,26 +1,31 @@
 #!/bin/bash
 
-RETCODE=$(fw_exists nimrod/bin/nim)
+RETCODE=$(fw_exists $IROOT/nim.installed)
 [ ! "$RETCODE" == 0 ] || { return 0; }
 
 test -d nimrod || git clone git://github.com/Araq/Nimrod.git nimrod
 cd nimrod 
+# post version 0.9.6 - most recent as of 2014-10-31
 git checkout bbb16713c1bbc266cb8d69f262cc302641e361c4
 
 test -d csources || git clone git://github.com/nimrod-code/csources.git
 cd csources
+# post version 0.9.6 - most recent as of 2014-10-31
 git checkout b0bcf88e26730b23d22e2663adf1babb05bd5a71
 sh build.sh
 cd ..
 
 bin/nimrod c koch
 
-# compile nim
+# bootstrapping nim's compiler
 ./koch boot -d:release
 
 # nim's package manager
 test -d nimble || git clone git://github.com/nimrod-code/nimble.git
 cd nimble
+# post version 0.4.0 - most recent as of 2014-10-31
 git checkout ecd78e0e0300a8178db320d83014d3eb47a89b4c
 ../bin/nim c src/nimble
 mv src/nimble ../bin/
+
+touch $IROOT/nim.installed