phases: add list of string to access phase name

phases: fix phase synchronization on push The bugs seemed to show up when element not in future common changeset should hold new hold phase data. The whole phase push machinery was rewritten in the process.

phases: implements simple revset symbol This changeset adds ``public()``, ``draft()`` and ``secret`` symbol for revset.

phases: store phase values in constant instead of using raw integer Phases constant are named after the phase name. Usage of integer have been replaced by proper constant.

sslutil: abort properly if no certificate received for https connection According to the documentation SSLSocket.getpeercert() can return None.

sslutil: work around validator crash getting certificate on failed sockets The previous workaround for correct handling of wrapping of failing connections might be enough to prevent this from happening, but the check here makes this function more robust.

sslutil: reorder validator code to make it more readable