Fix ldiff binary files comparison and output

Before this change, the comparison was reversed and diff were not
detected.

This commit also change the output when a diff is detected to look
like the GNU diff output.

Also fix the support of all other format than :report, by quickly
halting the diff process if there is a binary diff.

spec/fixtures/ldiff/output.diff.bin2

@@ -0,0 +1 @@
+Binary files spec/fixtures/file1.bin and spec/fixtures/file2.bin differ

spec/fixtures/ldiff/output.diff.bin2-c

@@ -0,0 +1 @@
+Binary files spec/fixtures/file1.bin and spec/fixtures/file2.bin differ

spec/fixtures/ldiff/output.diff.bin2-e

@@ -0,0 +1 @@
+Binary files spec/fixtures/file1.bin and spec/fixtures/file2.bin differ

spec/fixtures/ldiff/output.diff.bin2-f

@@ -0,0 +1 @@
+Binary files spec/fixtures/file1.bin and spec/fixtures/file2.bin differ

spec/fixtures/ldiff/output.diff.bin2-u

@@ -0,0 +1 @@
+Binary files spec/fixtures/file1.bin and spec/fixtures/file2.bin differ

spec/ldiff_spec.rb

@@ -8,6 +8,8 @@
   # standard:disable Style/HashSyntax
   fixtures = [
     {:name => "output.diff", :left => "aX", :right => "bXaX", :diff => 1},
+    {:name => "output.diff.bin1", :left => "file1.bin", :right => "file1.bin", :diff => 0},
+    {:name => "output.diff.bin2", :left => "file1.bin", :right => "file2.bin", :diff => 1},
     {:name => "output.diff.chef", :left => "old-chef", :right => "new-chef", :diff => 1},
     {:name => "output.diff.chef2", :left => "old-chef2", :right => "new-chef2", :diff => 1}
   ].product([nil, "-e", "-f", "-c", "-u"]).map { |(fixture, flag)|