fix include path of util.h
fix error when defining ENC28J60_CONTROL_CS to anything other than SS
Merge branch 'static-memory'
set ENC28J60_CONTROL_CS to SS as default
return 0 from Client.available() when Client is invalid (same as stock Ethernet-lib)
fix race-condition when remote closes connection while not all outstanding data is read
Merge branch 'master' into Arduino_1.5.5

Conflicts:
	UIPEthernet/src/utility/Enc28J60Network.cpp
	UIPEthernet/src/utility/Enc28J60Network.h