Add initial circle.yml file

Only half the OTP versions are enabled so far, and the build
will probably fail, but gotta start somewhere.

Makefile

@@ -11,6 +11,7 @@ dep_ct_helper = git https://github.com/extend/ct_helper.git master
 
 COMPILE_FIRST = ranch_transport
 PLT_APPS = crypto public_key ssl
+CI_OTP = OTP_R15B01 OTP_R15B02 OTP_R15B03-1 OTP_R16B01 OTP_R16B02 OTP_R16B03-1 # OTP-17.0.2 OTP-17.1.2 OTP-17.2.2 OTP-17.3.4 OTP-17.4.1 OTP-17.5.6.2 OTP-18.0.2
 
 # Standard targets.
 

circle.yml

@@ -0,0 +1,21 @@
+general:
+  artifacts:
+    - "logs"
+
+dependencies:
+  cache_directories:
+    - "~/.kerl"
+    - "~/erlang"
+
+  pre:
+    - sudo apt-get install autoconf2.59
+    - cd $HOME/bin && ln -s /usr/bin/autoconf2.59 autoconf
+    - cd $HOME/bin && ln -s /usr/bin/autoheader2.59 autoheader
+    - make ci-prepare:
+        timeout: 7200
+
+test:
+  override:
+    - source $HOME/erlang/OTP-18.0.2/activate && make dialyze
+    - make -k ci:
+        timeout: 3600