Update ex_doc to fix Elixir v1.5 deprecations

Author: alco

mix.lock

@@ -1,3 +1,3 @@
 %{"benchfella": {:hex, :benchfella, "0.3.1", "3728b082725f27c46502c4609f78b8db01d4739932ebfc59f350b7a2b47d394d", [:mix], []},
-  "earmark": {:hex, :earmark, "1.1.0", "8c2bf85d725050a92042bc1edf362621004d43ca6241c756f39612084e95487f", [:mix], []},
-  "ex_doc": {:hex, :ex_doc, "0.14.5", "c0433c8117e948404d93ca69411dd575ec6be39b47802e81ca8d91017a0cf83c", [:mix], [{:earmark, "~> 1.0", [hex: :earmark, optional: false]}]}}
+  "earmark": {:hex, :earmark, "1.2.3", "206eb2e2ac1a794aa5256f3982de7a76bf4579ff91cb28d0e17ea2c9491e46a4", [:mix], [], "hexpm"},
+  "ex_doc": {:hex, :ex_doc, "0.16.2", "3b3e210ebcd85a7c76b4e73f85c5640c011d2a0b2f06dcdf5acdb2ae904e5084", [:mix], [{:earmark, "~> 1.1", [hex: :earmark, repo: "hexpm", optional: false]}], "hexpm"}}