Spelling Fixes + Bump Travis Erlang Version (michalmuskala#90)

* fix spelling

* erlang 18.3 is no longer available, bump to 19

https://travis-ci.community/t/erlang-18-3-couldnt-be-pulled/3836

Author: arghmeleg

.travis.yml

@@ -17,7 +17,7 @@ matrix:
       elixir: 1.6
     - otp_release: 19.3
       elixir: 1.5
-    - otp_release: 18.3
+    - otp_release: 19.0
       elixir: 1.4
 
 install:

lib/encoder.ex

@@ -22,7 +22,7 @@ defprotocol Jason.Encoder do
       end
 
   If we were to call `@derive Jason.Encoder` just before `defstruct`,
-  an implementaion similar to the follwing implementation would be generated:
+  an implementation similar to the following implementation would be generated:
 
       defimpl Jason.Encoder, for: Test do
         def encode(value, opts) do
@@ -31,7 +31,7 @@ defprotocol Jason.Encoder do
       end
 
   If we called `@derive {Jason.Encoder, only: [:foo]}`, an implementation
-  similar to the following implementation would be genrated:
+  similar to the following implementation would be generated:
 
       defimpl Jason.Encoder, for: Test do
         def encode(value, opts) do