There's no need to include the build time, author, and copyright info
in the output of "fscrypt --version". This information is:

  - Overly complex (the current string is hard to parse)
  - Inaccurate (there are other authors than just me)
  - Unnecessary (the Apache 2 license is for Source Code)
  - Makes reproducible builds impossible

The default version string is just fine.

Signed-off-by: Joe Richey <joerichey@google.com>

Add support for 'fscrypt lock'.  This command "locks" a directory,
undoing 'fscrypt unlock'.

When the filesystem keyring is used, 'fscrypt lock' also detects when a
directory wasn't fully locked due to some files still being in-use.  It
can then be run again later to try to finish locking the files.

These were found by a combination of manual review and a custom script
that checks for common errors.

Also removed an outdated sentence from the comment for setupBefore().

Our current build tags set off the linter. We will later add in more
comprehensive build tags that will be properly formatted.

This command adds in the "fscrypt metadata" command. This command allows
advanced users to manipulate the metadata directly instead of just
creating a policy or protector as an option when encrypting a directory.

As some of these methods will require certain flags, error handling for
this case is also added. As the change passphrase method must indicate
when a old vs new password is necessary, additional KeyFuncs are added
which add this indicator.

Change-Id: Ibc92872088fae078df3c0eebd4f0cfcb7252d781

This commit adds in the status command, which has 2 functions, allowing
the user to query the state of the entire system or a specific
filesystem.

This commit also adds in the purge command to remove all policy keys
corresponding to a filesystem. This (along with getting the unlock
status for the status commands) uses additional keyctl functionality in
the crypto and actions packages.

Change-Id: Ic8e097b335c044c0b91973eff19753f363f4525d

This commit adds in the framework for adding commands and subcommands to
the fscrypt tool. This commit adds in the "setup", "encrypt", and
"unlock" commands. Additional information can be found by running:
    fscrypt <command> --help.

This commit defines how flags are parsed and errors are handled. It also
creates an extensible framework for prompting the user for information.

Change-Id: I159d7f44ee2b2bbc5e072f0802850e082d9a13ce