Fix encoding uncommon types

lib/raven/okjson.rb

@@ -81,7 +81,7 @@ def valenc(x)
     when false   then "false"
     when nil     then "null"
     else
-      raise Error, "cannot encode #{x.class}: #{x.inspect}"
+      strenc((x.inspect rescue $!.to_s))
     end
   end
 

spec/raven/okjson_spec.rb

@@ -20,6 +20,15 @@
     end
   end
 
+  it 'encodes anything that responds to to_s' do
+    data = [
+      Date.new(2014),
+      Rational(1),
+      (1..5)
+    ]
+    expect(Raven::OkJson.encode(data)).to eq '["#<Date: 2014-01-01 ((2456659j,0s,0n),+0s,2299161j)>",1/1,"1..5"]'
+  end
+
   it 'parses zero-leading exponent numbers correctly' do
     expect(Raven::OkJson.decode("[123e090]")).to eq [123000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000]
   end