pgsql: Improve PL/Python elog output When the elog functions (plpy.info

Log Message:
-----------
Improve PL/Python elog output

When the elog functions (plpy.info etc.) get a single argument, just print
that argument instead of printing the single-member tuple like ('foo',).

Modified Files:
--------------
pgsql/src/pl/plpython:
plpython.c (r1.131 -> r1.132)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/pl/plpython/plpython.c?r1=1.131&r2=1.132)
pgsql/src/pl/plpython/expected:
plpython_import.out (r1.2 -> r1.3)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/pl/plpython/expected/plpython_import.out?r1=1.2&r2=1.3)
plpython_spi.out (r1.3 -> r1.4)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/pl/plpython/expected/plpython_spi.out?r1=1.3&r2=1.4)
plpython_test.out (r1.12 -> r1.13)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/pl/plpython/expected/plpython_test.out?r1=1.12&r2=1.13)
plpython_trigger.out (r1.5 -> r1.6)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/pl/plpython/expected/plpython_trigger.out?r1=1.5&r2=1.6)
pgsql/src/pl/plpython/sql:
plpython_test.sql (r1.8 -> r1.9)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/pl/plpython/sql/plpython_test.sql?r1=1.8&r2=1.9)