add Stickler CI config (#564)

* add .stickler.yml

* update pr template

* update whatsnew

Author: wholmgren

.github/PULL_REQUEST_TEMPLATE.md

@@ -12,7 +12,7 @@ The following items must be addressed before the code can be merged. Please don'
  - [ ] Fully tested. Added and/or modified tests to ensure correct behavior for all reasonable inputs. Tests (usually) must pass on the TravisCI and Appveyor testing services.
  - [ ] Updates entries to `docs/sphinx/source/api.rst` for API changes.
  - [ ] Adds description and name entries in the appropriate `docs/sphinx/source/whatsnew` file for all changes.
- - [ ] Code quality and style is sufficient. Passes ``git diff upstream/master -u -- "*.py" | flake8 --diff``
+ - [ ] Code quality and style is sufficient. Passes LGTM and SticklerCI checks.
  - [ ] New code is fully documented. Includes sphinx/numpydoc compliant docstrings and comments in the code where necessary.
  - [ ] Pull request is nearly complete and ready for detailed review.
 

.stickler.yml

@@ -0,0 +1,7 @@
+linters:
+    flake8:
+        python: 3
+        max-line-length: 79
+files:
+    ignore:
+        - 'pvlib/_version.py'

docs/sphinx/source/whatsnew/v0.6.0.rst

@@ -167,6 +167,7 @@ Testing
 * Make test_forecast.py more robust. (:issue:`293`)
 * Improve test_atmosphere.py. (:issue:`158`)
 * Add LGTM.com integration. (:issue:`554`)
+* Add SticklerCI integration.
 
 
 Contributors