(network-#26) Loosen regex on interfaces provider

Given a Debian interfaces file if an `iface` line had two spaces between
iface and the network device the file would be marked as invalid. This
commit removes the single whitespace restriction.

This closes #26.

lib/puppet/provider/network_config/interfaces.rb

@@ -172,7 +172,7 @@ def self.parse_file(filename, contents)
         # iface <iface> <family> <method>
         # zero or more options for <iface>
 
-        if match = line.match(/^iface (\S+)\s+(\S+)\s+(\S+)/)
+        if match = line.match(/^iface\s+(\S+)\s+(\S+)\s+(\S+)/)
           name   = match[1]
           family = match[2]
           method = match[3]

spec/fixtures/provider/network_config/interfaces_spec/iface_whitespace

@@ -0,0 +1,10 @@
+# This file describes the network interfaces available on your system
+# and how to activate them. For more information, see interfaces(5).
+
+# The loopback network interface
+auto lo
+iface lo inet loopback
+
+# The primary network interface
+allow-hotplug eth0
+iface  eth0     inet   dhcp

spec/unit/provider/network_config/interfaces_spec.rb

@@ -50,6 +50,18 @@ def fixture_data(file)
       }
     end
 
+    it "should ignore variable whitespace in iface lines (network-#26)" do
+      fixture = fixture_data('iface_whitespace')
+      data = described_class.parse_file('', fixture)
+      data.find { |h| h[:name] == "eth0" }.should == {
+        :family  => "inet",
+        :method  => "dhcp",
+        :name    => "eth0",
+        :hotplug => true,
+        :options => {},
+      }
+    end
+
     it "should parse out lines following iface lines" do
       fixture = fixture_data('single_interface_static')
       data = described_class.parse_file('', fixture)