Restructure and bugfixes

• moved command checks into functions
• created main function
• fixed logic for disk status function. Should return all errors instead of failing on first error
• fixed output for some commands and help message

Fixed issues discribed in tickets

• fixed issue #2: using correct variable
• updated code according issue #3
• removed some duplicates in snmp_oids dict()
• updated some wrong variables names

v1.0

Removed icingaexchange.yaml for release