RFC operations for account security:

--new-account-key replaces the account key with a new one.
  Can modify the type or size as well. (update .cfg first)
  Does not affect certificate validity or pending operations.

--DEACTIVATE-account permanently deactivates the account on
  the server.  Per RFC, can not be revived.  Should not revoke
  existing certificates. (Server's choice.)

Added instructions on how to create a custom configuration template for domain configuration files

Signed-off-by: jeffmerkey <jeffmerkey@gmail.com>

Signed-off-by: jeffmerkey <jeffmerkey@gmail.com>

Signed-off-by: jeffmerkey <jeffmerkey@gmail.com>

Signed-off-by: jeffmerkey <jeffmerkey@gmail.com>

Signed-off-by: jeffmerkey <jeffmerkey@gmail.com>

Signed-off-by: jeffmerkey <jeffmerkey@gmail.com>

Signed-off-by: jeffmerkey <jeffmerkey@gmail.com>

Signed-off-by: jeffmerkey <jeffmerkey@gmail.com>

Add manual upgrade instructions for v2.43

Use `latest` tag instead of `master` in installation instructions

Use the GitHub release data to decide if an upgrade is available.

Only download the release if a newer stable release is published.

Install the full release - including the DNS scripts (requires "make")

Don't check for upgrades when restarting.

Remove --keep logic - only 1 old version is kept, only if make isn't available.
Old versions are availablel from the repo; if you have local changes, --upgrade doesn't make sense.

Can upgrade (or downgrade) to any tagged release with --experimental vx.yy

Note that GitHub API requests are rate-limited; this shouldn't be an issue
unless getssl is run more than ~60 times/hr.  If the limit is exceeded,
getssl will sleep until the limit is reset.  The limit is per-IP address.

The tests have been modified to only check for updates in the tests that
verify the check for updates logic.  This has the side effect of not
doing MANY pointless checks for updates in the tests...

Add --version
Update default endpoint to acme-v02.

Use a bash array to set several commands. (Commands use the usual syntax.)
The current syntax is unchanged when setting a single command.

```
README.md:1 MD041/first-line-heading/first-line-h1 First line in file should be a top level heading [Context: "![Run all tests](https://githu..."]
README.md:2 MD022/blanks-around-headings/blanks-around-headers Headings should be surrounded by blank lines [Expected: 1; Actual: 0; Above] [Context: "# getssl"]
```

Remove manual ACMEv1 -> ACMEv2 upgrade information