Generating missing private key with OpenSSL
Previously, if no existing key was found to sign the CRX with, the buildcrx binary was used. The binary we use right now, does not support this feature, thus, we should now generate missing keys with OpenSSL directly.
Fixed comment on private key generation task
Build process will abort if creating CRX failed
Merge pull request #3 from oliversalzburg/extension_builder

Generating missing private key with OpenSSL