Merge branch 'develop' into switchd_branching
Migrated base files from apps/topology
Migrated show_topology files from apps/topology
Add show_switch_status command
Add a binary heap implementaion.
Add utility functions for binary heap.
Add heap_utility_test.c
Moved show_{topology,switch_status} to examples/topology
Minimized show_topology example
Added sample .conf file
Add features test for topology C API
Refactor and merge apps/topology to trema.
remove dumper check from C API feature test
Workaround for Ubuntu 12.10 32bit (gcc-4.7) environment.
Rename libtopology -> topology.  C API part for #3.
Change message log level.
Add external attribute to output.
Log messages when enabling/disabling discovery.
log info level event on switch/port/link change event.
Log info level event only on link status change.
Move .features to match new features/ directory structure.