Use libpdcap+tar to extract files from archives

retrieving the small files back from the archives still relied on the
mounted namespace. This patch changes the script to directly use dcap to
read the file.
Completely use chimera-cli

Changed all remaining usages of the mounted namespace to use
alternatives
fix stat call

there was one call to chimera-cli stat that got a local filename, this
was reverted to a local stat call.
Fix URL for tar call

The URL passed to tar was missing the dcap:// info. This patch adds
this.