Change in apns certificate section headers

[Colleoni]

Hi,

I do not know if this library is still maintained as I see the last commit was three years ago. Anyway, today I have noticed that in new apns certificates the header -----BEGIN RSA PRIVATE KEY-----

has been substituted by -----BEGIN PRIVATE KEY-----

and same for -----END RSA PRIVATE KEY----- with -----END PRIVATE KEY-----

So I suggest to change the method _check_certificate in instapush/libs/apns to include this changes

def _check_certificate(ss):
    mode = 'start'
    for s in ss.split('\n'):
        if mode == 'start':
            if 'BEGIN RSA PRIVATE KEY' in s or 'BEGIN PRIVATE KEY' in s:
                mode = 'key'
        elif mode == 'key':
            if 'END RSA PRIVATE KEY' in s or 'END PRIVATE KEY' in s:
                mode = 'end'
                break
            elif s.startswith('Proc-Type') and 'ENCRYPTED' in s:
                raise Exception("The certificate private key should not be encrypted")
    if mode != 'end':
        raise Exception("The certificate doesn't contain a private key")

Hope this can help.

Best regards, Luca