use system locale for ports installation

I couldn't install the `sysutils/rubygem-bundler` port even though i changed my `LC_ALL` to `en_US.UTF-8`

    ===>  Building for rubygem-bundler-1.5.3
    ===> Compilation failed unexpectedly.
    Try to set MAKE_JOBS_UNSAFE=yes and rebuild before reporting the failure to
    the maintainer.
    *** Error code 1

    Stop.
    make: stopped in /usr/ports/sysutils/rubygem-bundler
    [ERROR   ] stderr: ERROR:  While executing gem ... (ArgumentError)
        invalid byte sequence in US-ASCII
    [INFO    ] Executing command 'pkg info -ao' in directory '/root'
    [ERROR   ] Failed to install sysutils/rubygem-bundler. Error message:
    ERROR:  While executing gem ... (ArgumentError)
        invalid byte sequence in US-ASCII
    [INFO    ] Completed state [sysutils/rubygem-bundler] at time 12:02:45.374921

Then i found out that salt was overwriting the locale, so after adding `reset_system_locale=False` it installed beautifully.

    [INFO    ] stdout: ===>  Building for rubygem-bundler-1.5.3
      Successfully built RubyGem
      Name: bundler
      Version: 1.5.3
      File: bundler-1.5.3.gem
    ===>  Staging for rubygem-bundler-1.5.3
    ===>   rubygem-bundler-1.5.3 depends on file: /usr/local/bin/gem21 - found
    ===>   rubygem-bundler-1.5.3 depends on file: /usr/local/bin/ruby21 - found
    ===>   Generating temporary packing list
    Successfully installed bundler-1.5.3
    1 gem installed
    Installing RDoc documentation for bundler-1.5.3...
    ====> Compressing man pages (compress-man)
    ===>  Installing for rubygem-bundler-1.5.3
    ===>  Checking if sysutils/rubygem-bundler already installed
    ===>   Registering installation for rubygem-bundler-1.5.3
    Installing rubygem-bundler-1.5.3... done
    ===>  Cleaning for rubygem-bundler-1.5.3
    [INFO    ] Executing command 'pkg info -ao' in directory '/root'
    [INFO    ] Installed Packages:
    rubygem-bundler changed from absent to 1.5.3