pgsnmpd - pgsnmpd: Add ability to read from YAML config file.

Log Message:
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Add ability to read from YAML config file. Adds requirement for libyaml

TODO: clean out the code that the YAML reader renders obsolete (i.e. code to support hardcoded test queries)

Modified Files:
--------------
    pgsnmpd:
        Makefile (r1.22 -> r1.23)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pgsnmpd/pgsnmpd/Makefile?r1=1.22&r2=1.23)
        customquery.c (r1.5 -> r1.6)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pgsnmpd/pgsnmpd/customquery.c?r1=1.5&r2=1.6)
        customquery.h (r1.1 -> r1.2)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pgsnmpd/pgsnmpd/customquery.h?r1=1.1&r2=1.2)

Added Files:
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    pgsnmpd:
        query_reader.c (r1.1)

(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pgsnmpd/pgsnmpd/query_reader.c?rev=1.1&content-type=text/x-cvsweb-markup)
        query_reader.h (r1.1)

(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pgsnmpd/pgsnmpd/query_reader.h?rev=1.1&content-type=text/x-cvsweb-markup)
        test.yaml (r1.1)

(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pgsnmpd/pgsnmpd/test.yaml?rev=1.1&content-type=text/x-cvsweb-markup)