Use OpenSSL for ECDSA validation

Removes dependency on GMP and mdanter/ecc

Signed-off-by: Floris Bos <bos@je-eigen-domein.nl>
Convert public key to PEM without phpseclib

Since the public key parameters and length are fixed, we don't need
a full fledged ASN.1 encoder class, and can hardcode those.

Signed-off-by: Floris Bos <bos@je-eigen-domein.nl>
Use OpenSSL for attestion certificate validation

Removes dependency on phpseclib

Signed-off-by: Floris Bos <bos@je-eigen-domein.nl>
Fix PHP 5.3 compatibility

Use \x12 hex string instead of hex2bin()
because hex2bin is only available starting with PHP 5.4

Signed-off-by: Floris Bos <bos@je-eigen-domein.nl>
Use 'sha256' instead of 'OPENSSL_ALGO_SHA256' constant

PHP versions older than 5.4 do not have OPENSSL_ALGO_SHA256

Signed-off-by: Floris Bos <bos@je-eigen-domein.nl>
mark hhvm as allowed failure for travis
print a bit of information on failing test
fix the debug printing in the test
TOO_LOW, not TO_LOW
check the request challenge on authenticate

fixes #6
clearer documentation about the counter field and errors

relates to #5
Use tab to indent instead of space
More readable!
Throw Exception
Fix Tests
Update example(PDO)
Oops.
Fix class name typo
Use PUBKEY_LEN instead of hard coding
Add argument type check

More checks will be added soon.