iperf3 3.1.3

Also, formula cleanups:
- moved bottle block above head block
- fixed spacing issue with comment on line 29

Closes #2775.

Signed-off-by: Dominyk Tiller <dominyktiller@gmail.com>

Formula/iperf3.rb

@@ -3,16 +3,8 @@ class Iperf3 < Formula
   homepage "https://github.com/esnet/iperf"
 
   stable do
-    url "https://github.com/esnet/iperf/archive/3.0.11.tar.gz"
-    sha256 "c774b807ea4db20e07558c47951df186b6fb1dd0cdef4282c078853ad87cc712"
-  end
-
-  head do
-    url "https://github.com/esnet/iperf.git"
-
-    depends_on "libtool" => :build
-    depends_on "automake" => :build
-    depends_on "autoconf" => :build
+    url "https://github.com/esnet/iperf/archive/3.1.3.tar.gz"
+    sha256 "e34cf60cffc80aa1322d2c3a9b81e662c2576d2b03e53ddf1079615634e6f553"
   end
 
   bottle do
@@ -23,10 +15,18 @@ class Iperf3 < Formula
     sha256 "391b1e77cf0805e7fab56c14a6fa5e8aa832ad43da77f320e5150c4b69547f5c" => :mountain_lion
   end
 
+  head do
+    url "https://github.com/esnet/iperf.git"
+
+    depends_on "libtool" => :build
+    depends_on "automake" => :build
+    depends_on "autoconf" => :build
+  end
+
   def install
     system "./bootstrap.sh" if build.head?
     system "./configure", "--prefix=#{prefix}"
-    system "make", "clean"      # there are pre-compiled files in the tarball
+    system "make", "clean" # there are pre-compiled files in the tarball
     system "make", "install"
   end