Add import mac2ip mapping from file

 - Add function get_mac2ip_from_file to read the mapping as a dict
 - Add settings parameter mac2ip_file to state the file
 - Add initial mapping parameter to the Mac2ip class constructor
 - Add settings parameter arpscan_interfaces to restrict network
   interfaces for arp scanning
 - Remove the InterfaceDiscoverError exception because it's needless
Add new class for mac addresses in separated file
Add the mapping of mac prefixes to vendors

 - Download the oui.txt file containing the mapping
 - Add the function get_vendors_list reading the file and returning the
   mapping as a dictionary
 - Add support of mac prefixes to the normalize_mac function
Exclude temporary vim files from git tracking

and fix errors in names of constant of LOG_ERR
Add AddressDict class in the separated file

Now all addressess (macs, ips, hostnames) will be stored by the only
AddressDict object. The object is a dictonary where keys are mac
addresses, values are Mac objects. The Mac object contains mac address,
ip address and hostname
Move my personal excludes to global config
Add extra methods to the AddressDict class

 - Add methods update, contains, resolve_ips
 - Change the name attribute to the property method
Improve the get_addresses_from_file function

Remove normalization of mac addresses and add support of comments
Add function to show addresses in readable format

It contains in the Mac class and will be used to present data to zabbix.
New function has replaced the old __repr__
Add get and update_from functions
Move the resolv function from AddressDict to Mac
Change in Mac and AddressDict classes

 - Move the update function into the Mac class
 - Combine update_from function of AddressDict into the one and rename
   it to import_from
Add the show function in the AddressDict class
Import the import_from function in AddressDict

The function can import addresses from lists, tuples, sets of mac
addresses.
Rewrite code for working with AddressDict class
Remove data requests from switch initialization

It allows to combine two blocks of code into the update_data function
Remove files containing unnecessary classes
Move execution of snmpwalk command in smonitor.py

It allows to log execution and output of the command. Besides it's added
the show_mapping function to print mappings (dict and list of tuples) in
standard format.
Add new parameters in Settings module

 - The arpscan_only parameter to restrict network interfaces allowed for arp
   scanning
 - The vendors_file parameter containing mapping mac address prefixes to
   vendors
 - The addresses_file parameter containing custom mapping mac addresses
   to ip and hostname
Fix bug in the snmpwalk function

The application shut down in case of error of the snmpwalk command,
because error message template used undefined variable.