Update i18n.json

Engadida a lingua galega (gl).
Update I18nTest.java

Fix test failure:

Running gherkin.I18nTest
Tests run: 6, Failures: 1, Errors: 0, Skipped: 0, Time elapsed: 0.376 sec <<< FAILURE!
shouldFindAllLanguages(gherkin.I18nTest)  Time elapsed: 0.094 sec  <<< FAILURE!
java.lang.AssertionError: expected:<[ar, bg, bm, ca, cs, cy-GB, da, de, el, en, en-Scouse, en-au, en-lol, en-old, en-pirate, en-tx, eo, es, et, fa, fi, fr, he, hi, hr, hu, id, is, it, ja, ko, lt, lu, lv, nl, no, pl, pt, ro, ru, sk, sr-Cyrl, sr-Latn, sv, tl, tr, tt, uk, uz, vi, zh-CN, zh-TW]> but was:<[ar, bg, bm, ca, cs, cy-GB, da, de, el, en, en-Scouse, en-au, en-lol, en-old, en-pirate, en-tx, eo, es, et, fa, fi, fr, gl, he, hi, hr, hu, id, is, it, ja, ko, lt, lu, lv, nl, no, pl, pt, ro, ru, sk, sr-Cyrl, sr-Latn, sv, tl, tr, tt, uk, uz, vi, zh-CN, zh-TW]>
Update i18n_spec.rb

Fix test failure, gl Galician galego added.
Merge branch 'master' of git://github.com/son-cativo/gherkin
Added Galician