Revert "Need to test, but added ICMP"

This reverts commit b275e91a945ed58f653f6adf9fca13ed6a078064.
Fixed bugs regarding cache

Cache should work now, please look at the cache output on ./sr window
to confirm that handle request is sending and receiving the correct arp
requests
Fixed bug in ip routing and now wget worksc
Merge branch 'master' into testing

Conflicts:
	router/sr_icmp.c
	router/sr_icmp.h
Revert "Merge branch 'master' into testing"

This reverts commit 2f3beff01b8be93be280db9d9eaed4519a254fec, reversing
changes made to 02f8814e87211a9cc60fe04ea910554af34f3dbf.
Merge branch 'testing'