Merge pull request #1315 from jboeuf/security_connector

BUILD

Makefile

build.json

src/core/httpcli/httpcli.c

src/core/httpcli/httpcli_security_connector.c

src/core/httpcli/httpcli_security_connector.h

src/core/security/auth.c

src/core/security/credentials.c

src/core/security/credentials.h

src/core/security/factories.c

src/core/security/secure_transport_setup.c

src/core/security/secure_transport_setup.h

src/core/security/security_connector.c

src/core/security/security_connector.h

src/core/security/server_secure_chttp2.c

src/core/surface/secure_channel_create.c

src/ruby/spec/credentials_spec.rb

test/core/end2end/fixtures/chttp2_fake_security.c

test/core/end2end/fixtures/chttp2_simple_ssl_fullstack.c

...nd2end/fixtures/chttp2_simple_ssl_with_oauth2_fullstack.c