Adding Phone To helper like mail_to for handling phone numbers

Adding Phone To helper like mail_to for handling phone numbers

Useful for mobile browsers and desktop browser with phone supported software.

Creates a tel link tag to the specified +phone_number+

Accepts blocks

Distributed into 
```ruby  
def test_phone_to_generates_default_link
    assert_dom_equal %{<a href="tel:+112345678">+112345678</a>}, phone_to("+112345678")
  end

  def test_phone_to_generates_text_and_link
    assert_dom_equal %{<a href="tel:+112345678">Call me</a>}, phone_to("+112345678", "Call me")
  end

  def test_phone_to_honurs_html_options
    assert_dom_equal(
        %{<a class="admin" <a href="tel:+112345678">Call me</a>},
        phone_to("+112345678", "Call me", "class" => "admin")
    )
    assert_equal phone_to("+112345678", "Call me", "class" => "admin"),
                 phone_to("+112345678", "Call me", class: "admin")
  end
```