chore(composer): remove composer.lock from depot

chore(deps): add guzzlehttp/guzzle

feat(client): Update to API specification v2.6

feat(client): Update to API specification v2.4

feat(client): Update to API specification v2.3

update(pkg): bump version

update(client): regenerate from api specs

fix(build): reserved words in enums

Ref. swagger-api/swagger-codegen#5356
Ref. swagger-api/swagger-codegen#5357

doc(readme): s/master/dev-master/

chore(package): bootstrap javascript api client