add preliminary support for exinda / gfi traffic shapers (#283)

* exinda support

* exinda support

* add exinda hint

needed to identify exinda devices.

* mentin exinda in overview and link docs

* overwrite layers to l2/3/4/7

* get uptime from exinda mib

now matches uptime reported by cli & web interface.

* single quotes preferred

* to much copy/paste

* merge 3.63

* some more functions added. also general cleanup

* Update .travis.yml

* a few fixes

* Update .travis.yml

* Update .travis.yml

* revert

* revert

META.json

@@ -232,6 +232,10 @@
          "file" : "lib/SNMP/Info/Layer2/CiscoSB.pm",
          "version" : "3.63"
       },
+      "SNMP::Info::Layer2::Exinda" : {
+         "file" : "lib/SNMP/Info/Layer2/Exinda.pm",
+         "version" : "3.63"
+      },
       "SNMP::Info::Layer2::HP" : {
          "file" : "lib/SNMP/Info/Layer2/HP.pm",
          "version" : "3.63"