add rubyntlm dependency which seems to be required

In response to error:
```
$ possible_email search jon gautsch workmein.com
/Users/jgautsch/.rvm/gems/ruby-2.1.2/gems/httpi-2.2.5/lib/httpi/adapter/net_http.rb:12:in `<top (required)>': Invalid version of rubyntlm. Please use v0.3.2+. (ArgumentError)
	from /Users/jgautsch/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55:in `require'
	from /Users/jgautsch/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55:in `require'
	from /Users/jgautsch/.rvm/gems/ruby-2.1.2/gems/httpi-2.2.5/lib/httpi.rb:8:in `<top (required)>'
	from /Users/jgautsch/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55:in `require'
	from /Users/jgautsch/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55:in `require'
	from /Users/jgautsch/.rvm/gems/ruby-2.1.2/gems/possible_email-0.0.1/lib/possible_email.rb:6:in `<top (required)>'
	from /Users/jgautsch/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55:in `require'
	from /Users/jgautsch/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55:in `require'
	from /Users/jgautsch/.rvm/gems/ruby-2.1.2/gems/possible_email-0.0.1/bin/possible_email:3:in `<top (required)>'
	from /Users/jgautsch/.rvm/gems/ruby-2.1.2/bin/possible_email:23:in `load'
	from /Users/jgautsch/.rvm/gems/ruby-2.1.2/bin/possible_email:23:in `<main>'
	from /Users/jgautsch/.rvm/gems/ruby-2.1.2/bin/ruby_executable_hooks:15:in `eval'
	from /Users/jgautsch/.rvm/gems/ruby-2.1.2/bin/ruby_executable_hooks:15:in `<main>'
```