Miscellaneous minor fixes

[nosnilmot]

Various minor fixes to tsung_stats.pl:

• Use #!/usr/bin/env to permit choice of perl binary
• add --allgraph option to to generate all graph and image formats
• minor graph updates

And fix view-only mode (tsung view) [fixes #386 & #395]:

• rewrite image references to absolute paths
• fix path lookup when not running full tsung controller
• specify template_path on tsung view commandline