Merge pull request #2252 from jboeuf/jwt_verifier

BUILD

Makefile

build.json

gRPC.podspec

src/core/httpcli/httpcli.h

src/core/security/credentials.c

src/core/security/jwt_verifier.c

src/core/security/jwt_verifier.h

test/core/security/jwt_verifier_test.c

test/core/security/print_google_default_creds_token.c

test/core/security/verify_jwt.c

tools/doxygen/Doxyfile.core.internal

tools/run_tests/sources_and_headers.json

tools/run_tests/tests.json

vsprojects/Grpc.mak

vsprojects/grpc/grpc.vcxproj

vsprojects/grpc/grpc.vcxproj.filters