Better to have all formatting on the client side, so we format the
header and the reponse values in the same place. (Also no need to
send this data over the wire as it's always the same).

OptionStrList takes a filename as its value. It reads the file into a
list of strings in the protobuf. On the server side, the values are
unpacked and made available as std::vector<std::string>.

For example implementation, see "cta-admin repack add"

Default now set to 10s. Note that XRD_TIMEOUTRESOLUTION must be set
<= 10s, otherwise timeout defaults to 15s.

This allows specifying different protocol buffers for EOS and CTA Admin
messages, both of which must be processed by the same XRootD plugin in
the CTA Frontend.

Use precision .00 for Mbytes. Move library name to the front.

Converted all bytes to Mbytes. Removed extra space in the output.
Reordered fields.

First version of a streaming "cta archivefile ls" command.

Fixed the timings so they show up in all states.
Removed lds command.
Added error message when a drive is not found for single drive ls.

Removed the member variable XrdCtaFile::error that was incorrectly
shadowing XrdSfsFile::error.

Added the XrdCtaFile::m_listingArchiveFiles member variable and
factorized XrdCtaFile::readFromCmdlineOutput() out from
XrdCtaFile::read() so that in the future the XrdCtaFile::read()
method will be able to treat the listing of archive files
differently from other cta commands.

Currently none of the cta commands are incrementally generating
and streaming large result sets back to the cta command-line
tool.  All commands are generating the entire result in the
constructor of XrdCtaFile.  The result is streamed back to the
cta command-line tool, but the result is generated in one
single stepi before any streaming starts.

The listing of archive files is being gradually modified to
incrementaly generate the result in each call to
XrdCtaFile::read().  This commit is one step in this
larger modification.

Removed unnecessary member variable XrdCtaFile::m_cmdlineReturnCode

Removed unused int return from logRequestAndSetCmdlineResult().

Simplified the XrdCtaFile class.  logRequestAndSetCmdlineResult()i
is now only called by XrdCtaFile::open().

This reverts commit 341d1c7f.

After much discussion the commit being reverted has and would have
generated more work than problems solved.

Before this commit, Daniele had hardcoded into the CTA
front-end the constraint that CTA admins must be
authenticated by krb5.

This commit drops this contraint for two reasons:

1. The xrootd/EOS configuration files already require
   operators to specify which authentication methods can
   be used.  Daniele’s constraint is not needed to
   further enforce security, it only serves to constrain
   admin authentication to krb5 which I personally do not
   see as providing any added value.

2. The CERN infrastructure uses krb5, other sites like
   RAL do not.

Removed the reconciliation command (will be done by EOS: both the CTA side and the EOS side reconciliation)

Added stub for supporting disk instance authorization (to be discussed how to implement this in the catalogue)