pgsql: Rename default text search parser's "uri" token type to

Log Message:
-----------
Rename default text search parser's "uri" token type to "url_path",
per recommendation from Alvaro.  This doesn't force initdb since the
numeric token type in the catalogs doesn't change; but note that
the expected regression test output changed.

Modified Files:
--------------
    pgsql/doc/src/sgml:
        textsearch.sgml (r1.27 -> r1.28)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/textsearch.sgml?r1=1.27&r2=1.28)
    pgsql/src/backend/snowball:
        snowball.sql.in (r1.5 -> r1.6)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/snowball/snowball.sql.in?r1=1.5&r2=1.6)
    pgsql/src/backend/tsearch:
        wparser_def.c (r1.4 -> r1.5)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/tsearch/wparser_def.c?r1=1.4&r2=1.5)
    pgsql/src/test/regress/expected:
        tsearch.out (r1.6 -> r1.7)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/tsearch.out?r1=1.6&r2=1.7)