推送证书生成

生成pem步骤：
1.下载下来你配置好的推送证书aps_developer_identity.cer 文件。
2.转换 .cer 文件到 .pem 文件:
openssl x509 -in aps_developer_identity.cer -inform der
-out PushChatCert.pem
3.在把你“钥匙”推送证书导出成的.p12到.pem文件:
openssl pkcs12 -nocerts -out PushChatKey.pem -in PushChatKey.p12
Enter Import Password:
MAC verified OK
Enter PEM pass phrase:
Verifying - Enter PEM pass phrase:
4.合并两个pem文件：cat PushChatCert.pem PushChatKey.pem > ck.pem
5.测试证书是否可用：
openssl s_client -connect gateway.sandbox.push.apple.com:2195
-cert PushChatCert.pem -key PushChatKey.pem