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(-)