Fix cookie authentication; always show version information

[johnsonjh]

• Use .pktcookie for the cookie file name
• Better log output, mention authorization, etc
• Make rpcclient actually use the cookie data
• Try user specified user/pass before the cookie
• Implement cookie data authentication cache
• Unconditionally output pktd version information

[johnsonjh]

This is a Travis false positive that is already fixed in #144

[johnsonjh]

Likely depends on PR #132 for proper behavior.

[cjdelisle]

conflicts

[johnsonjh]

Will fixup

[johnsonjh]

@cjdelisle autorebased

[johnsonjh]

• Verified clean merge with recursive strategy against develop as of Thu Nov 26 02:01:32 PM EST 2020 + PR Improvement in bbolt/walletdb speed #111 + PR More reliably detect if we are current (or not.) #142 + PR Fix bug where pktctl -h would show help twice. #151 + PR blockchain: Avoid deadlock with additional locking #156 + PR peer: Default to 1s default trickle interval #160 + PR Optimization: Compare strings to a null string directly #168

Auto-merging pktd.go
Auto-merging config.go
Merge made by the 'recursive' strategy.
 config.go                   | 10 +++-----
 pktconfig/util.go           |  4 +--
 pktd.go                     | 14 ++++++++---
 rpcclient/cookiefile.go     | 41 ++++++++++++++++++++++++++++++
 rpcclient/infrastructure.go | 61 +++++++++++++++++++++++++++++++++++++++++++--
 5 files changed, 116 insertions(+), 14 deletions(-)
 create mode 100644 rpcclient/cookiefile.go

[johnsonjh]

• NOTE: Applied to WIP rebase branch successfully after manual rebase.