Configure appveyor (#142)

with much appreciation to @michaeltryby 🎉 

* Initial commit getting Appveyor running
* Modifying branch built
* Modifying generator
* Modifying path to test scripts
* Modifying path to test scripts
* Configuring appveyor cache to store cmake generated build files
* suppressing insecure string warnings
* Fixing typo
* Fixing problem with cmake build invocation
* Changing CMake to Linux build on Travis
* Adding compiler flags for MSVC
* Adding Appveyor build status badge
* Adding Appveyor build status badge
* Adding include directory so it is available to project files
* cleaning cache
* rebuilding cache

appveyor.yml

@@ -0,0 +1,48 @@
+#
+#  appveyor.yml - Appveyor CI configuration for OWA EPANET
+#
+#  Date created: 01/09/2018
+#
+#  Author: Michael E. Tryby
+#          US EPA - ORD/NRMRL
+# 
+
+version: 2.0.{build} 
+
+image: 
+  - Visual Studio 2013
+
+# called before repo cloning
+init: 
+  - set EPANET_HOME=%APPVEYOR_BUILD_FOLDER%
+  - set BUILD_HOME=buildprod
+  - set TEST_HOME=tests\epanet-nrtestsuite
+  - set NRTEST_SCRIPT=%EPANET_HOME%\%BUILD_HOME%\packages\nrtest\scripts
+  - set GENERATOR="Visual Studio 10 2010"
+
+cache: 
+  - C:\ProgramData\chocolatey\bin -> appveyor.yml
+  - C:\ProgramData\chocolatey\lib -> appveyor.yml
+  - '%BUILD_HOME% -> CMakeLists.txt'
+
+# called after repo clone
+install: 
+  - choco install swig
+  - python -m pip install --src %BUILD_HOME%\packages -r tools\requirements.txt
+
+# called before build
+before_build:
+  - cd %BUILD_HOME%
+  - cmake -G %GENERATOR% -DCMAKE_BUILD_TYPE=Release ..
+
+# run custom build script
+build_script: 
+  - cmake --build . --target runepanet --config Release 
+
+before_test:
+  - cd %EPANET_HOME%
+  - tools\gen-config.cmd %EPANET_HOME%\%BUILD_HOME%\bin\Release > %TEST_HOME%\apps\epanet-%APPVEYOR_REPO_COMMIT%.json 
+
+# run custom test script
+test_script:
+  - tools\run-nrtest.cmd %NRTEST_SCRIPT% %TEST_HOME% %APPVEYOR_REPO_COMMIT%