pgsql: Add json_array_elements_text function.

Add json_array_elements_text function.

This was a notable omission from the json functions added in 9.3 and
there have been numerous complaints about its absence.

Laurence Rowe.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/5264d9154178d3aeaa0359b43a450298a7ce7281

Modified Files
--------------
doc/src/sgml/func.sgml | 21 +++++++++++
src/backend/utils/adt/jsonfuncs.c | 67 ++++++++++++++++++++++++++++------
src/include/catalog/pg_proc.h | 2 +
src/include/utils/json.h | 1 +
src/test/regress/expected/json.out | 34 +++++++++++++++--
src/test/regress/expected/json_1.out | 34 +++++++++++++++--
src/test/regress/sql/json.sql | 6 ++-
7 files changed, 143 insertions(+), 22 deletions(-)