Add: Give a better report on unexpected errors and allow to give explicitely an args array to the plugin.

Propose to submit bug report.
Cleaned shinkenplugins.BasePlugin

- Better exit()
- Use unknown() method where possible
- Use self.x instead of self.__class__.x
- Better use of usage()
Enh shinkenplugins package with a unique version string.

Use a VERSION text file, read by setup.py and by package itself.
shinkenplugins: VERSION file need to be added as package_data.

Also import __version__ from package's __init__.
Plugins requirements: requires shinkenplugins>=0.1.4 (latest) but < 0.2 !

To prevent futur conflict when shinkenplugins lib will have been rewritten.
init: split ongoing..
BasePlugin: Better usage.
BasePlugin: give better report on unexpected error.

Propose to submit bug report with traceback and versions and arguments provided.
clean: x.__class__.y <=> x.y ; when y hasn't been rebound on the instance.
Merge branch 'BasePlugin_refactorization'

Begin of a refactorization and clean of shinkenplugins package.
For now only

- a split of previous classes/things to different modules has been done.
- a slight clean of them.

A rewrite of the BasePlugin will be tried later.
decode fixed
imported arprequest from PyPI.
Adapted arprequest.
arp_no_change: Added files and implemented first "basic" check.
Moved arprequest body into check_arp_no_change.
arp_no_changed: implemented a simpler version using /usr/bin/arp tool.
added symbolic link
add .py extension to script