Added json-metalist program to report metadata given a JSON stream

Added a new baton_error_t parameter to json_to_path to detect errors
in user input

Fixed a double free on error bug on the query_input argument to
do_query
Merge branch 'devel' of github.com:keithj/baton into devel
Merge pull request #26 from keithj/devel

Added json-metalist program
Updated README
Explicitly set results pointer to NULL for cleanup on errors
Merge pull request #27 from keithj/devel

Updated README
Free memory allocated when the client unpacks structs from the server

No longer pretty-print JSON responses
Added ability to define AVU queries in JSON

Updated configure.ac for newer autoconf

Require autoconf 2.68
Merge pull request #29 from keithj/devel

Free memory allocated when the client unpacks structs from the server
Merge pull request #30 from keithj/json_query

Added ability to define AVU queries in JSON
Merge pull request #31 from wtsi-npg/json_query

Json query
Merge remote-tracking branch 'wtsi-npg/master'