documentation overhaul (#353)

* ident
* remove $Id$ tags from rcs software which has been retired
* make an effort to sync required mib docs with actual code
* sync even more docs with what code actually does
* some whitespace nits
* fixup example to use snmpv2 for all but the most ancient devices
* remove blurb to find more specific snmp::info classes for classes
  which alrdy are as specific as they can get (eg snmp::info::layer3::vmware
  doesn't need info on to find a specific module since there ain't none)
* rename all sub {vendor} strings to lowercase vendor, if cisco, juniper
  and arista can be lowercase, so can be all the rest.
* fix tests
* spread some use warnings around
* use $ instead of @
* remove defines that are included via parent classes
* use strict + warnings
* remove alrdy included modules
* add comma after last list item
* typos
* mibs are found in our mib repo, not on the cisco site
* documentation fixes

lib/SNMP/Info/Layer3/Tasman.pm

@@ -102,7 +102,7 @@ my $module_map = {
     DS3_1C  => '1-port Channelized T3',
     WTE_1   => '1-port T1/E1 w DS0 and DS1 support for both TDM and Packet',
     WTE_2S  => '2-port Sync and Async Serial',
-    WTE_8   => '8-port T1/E1'
+    WTE_8   => '8-port T1/E1',
 };
 
 sub vendor {