some Ruby 2.4-ism's in the tree

[busterb]

Using Ruby 2.4 can be a little tricky - while that's the version we have in-tree and the one we package with omnibus, not everyone has upgraded yet, so a few things are broken in 2.3:

[05/17/2017 13:16:47] [e(0)] core: Unable to load module /root/metasploit-framework/modules/exploits/linux/smtp/haraka.py NoMethodError undefined method `match?' for #String:0x0055db7406e9d8

It looks like we're using String.match? in a few places that could be fairly easily converted to use String.match (I'm guilty of a couple, will fix tomorrow if someone doesn't beat me to it.)

lib/msf/core/exploit/powershell.rb:    return script_in unless script_in.match?(/FromBase64String/)
lib/msf/core/modules/external/bridge.rb:    module_name.match? /\.py$/
modules/exploits/linux/http/huawei_hg532n_cmdinject.rb:    if res.body.match? invalid_port_export_marker
modules/exploits/linux/http/huawei_hg532n_cmdinject.rb:          if result.match? regex
modules/exploits/linux/misc/quest_pmmasterd_bof.rb:    if res.match? "Pong4$"

[busterb]

I wonder if including https://github.com/marcandre/backports and calling it a day might be simpler and allow adopting newer idioms more quickly.

[busterb]

I added the backports Library above ^ which appears to fix the issue for Ruby 2.3. Any objections to this approach?