Added FormatJson::parse( $value, $options = 0 ) returning Status

Added FormatJson::parse( $value, $options = 0 ) returning Status

* Returns Status object that will contain decoded value on success
* Adds i18n messages for all available PHP JSON errors

ATTN Translation team: please copy these messages:

gwtoolset-json-error-depth => json-error-depth
gwtoolset-json-error-state-mismatch => json-error-state-mismatch
gwtoolset-json-error-ctrl-char => json-error-ctrl-char
gwtoolset-json-error-syntax => json-error-syntax
gwtoolset-json-error-utf8 => json-error-utf8

Change-Id: I1c4f37aaabad369b75a1fbd223fad27ebcfe1c3c