Adds PR template (#180)

* Adds PR template

DEV adds default pull request template to help remind contributors to use PR commit message tags.

pull_request_template.md

@@ -0,0 +1,24 @@
+Please remember to apply all applicable tags to your pull request:
+----
+Our release notes are automatically generated from the commit messages.  Please structure your commit message using these tags to simplify the release notes processs.
+
+Example:
+----
+
+    Subject: Improvements to matMul. (#900)
+
+    Body:
+    FEATURE Add transpose bits to matmul.
+    PERFORMANCE Improve matMul CPU speed by 100%.
+
+Tags:
+----
+* FEATURE -- (when new functionality / API is added)
+* BREAKING -- (when there is API breakage)
+* BUG -- (bug fixes)
+* PERF -- (performance improvements)
+* DEV -- (development flow changes)
+* DOC -- (documentation changes) 
+* SECURITY -- (security changes) 
+* MISC -- If no tag is specified, it will be put under a "MISC" tag.
+