openflow_input: add bsn_disable_src_mac_check extension instruction
add bsn_disable_src_mac_check testcase
java_gen: support extension instructions
java_gen: support testing classes without builders

Some classes, like OFInstructionBsnDisableSrcMacCheck, don't have any data
members and so have a single immutable instance and no builder. This change
fixes the unit tests to use the correct factory method.
pyloxi: support of_instruction_bsn_disable_src_mac_check
loci: support of_instruction_bsn_disable_src_mac_check
OFPortBitMap: add functionality to iterate over the Ports

+ a factory function from a OFBitMask
Merge branch 'master' of github.com:floodlight/loxigen
Merge into master from pull request #141:
Fix return types for OFActionPopMpls and OFActionSetNwDst LOXI-51 LOXI-52 (https://github.com/floodlight/loxigen/pull/141)
pyloxi: fix special parsing case for experimenter instructions
Merge into master from pull request #139:
add bsn_disable_src_mac_check instruction (https://github.com/floodlight/loxigen/pull/139)
Merge into master from pull request #140:
OFPortBitMap: add functionality to iterate over the Ports (https://github.com/floodlight/loxigen/pull/140)
Use hamcrest-integration library to use additional matchers
Merge into master from pull request #142:
Use hamcrest-integration library to use additional matchers (https://github.com/floodlight/loxigen/pull/142)