lrdp-v2: README: ramparse.py: add more help about python2.7

If the user has python2.7 installed but it's not the default interpreter
on their system, they might get confused when they invoke the parser and
get a message about needing to install 2.7 even though they already have
it installed. Add some instructional messages about this situation to
the 2.6 invocation warning message as well as the README.

Change-Id: Ib1ee7df39199f715b236dbda2f75093ba0501648

linux-ramdump-parser-v2/README

@@ -49,6 +49,17 @@ Python 2.7 is required to run this tool. It can be downloaded and
 installed from https://www.python.org/ or through your system's
 software package manager.
 
+If you already have python2.7 installed but it's not the default
+python2 interpreter on your system (e.g. if python2 points to
+python2.6) then you'll need to invoke the script with python2.7
+explicitly, for example:
+
+    $ python2.7 $(which ramparse.py) ...
+
+instead of:
+
+    $ ramparse.py ...
+
 Setting up the toolchains
 -------------------------------
 The parser relies on having access to gdb and nm to work. You will need to

linux-ramdump-parser-v2/ramparse.py

@@ -40,12 +40,23 @@ if major != 2:
 if minor != 7 and '--force-26' not in sys.argv:
     from textwrap import dedent
     print(dedent("""
-    Warning! This script is developed and tested with Python 2.7.
+    WARNING! This script is developed and tested with Python 2.7.
     You might be able to get things working on 2.6 by installing
     a few dependencies (most notably, OrderedDict [1])
     and then passing --force-26 to bypass this version check, but
     the recommended and supported approach is to install python2.7.
 
+    If you already have python2.7 installed but it's not the default
+    python2 interpreter on your system (e.g. if python2 points to
+    python2.6) then you'll need to invoke the scripts with python2.7
+    explicitly, for example:
+
+        $ python2.7 $(which ramparse.py) ...
+
+    instead of:
+
+        $ ramparse.py ...
+
     [1] https://pypi.python.org/pypi/ordereddict"""))
     sys.exit(1)
 if '--force-26' in sys.argv: