Switch to rebar build tool

Use dynamic Rebar configuration
Make iconv dependency optional
Disable transient_supervisors compile option
Add hipe compilation support
Only compile ibrowse and lhttpc when needed
Make it possible to generate an OTP application release
Add --enable-debug compile option
Add --enable-all compiler option
Add --enable-tools configure option
Add --with-erlang configure option.
Add --enable-erlang-version-check configure option.
Add lager support
Improve the test suite