add / update recipes and build changes for Python 3.6.6 compatibility (#315)

* add / update recipes and build changes for Python 3.6.6 compatibility
* include Python 3 apt packages in travis build script
* use Python 3.6 in Travis
* Enable _blake2 and _sha3 in Python 3. Remove unnecessary files.
* change zope.interface version
* update cffi version

p4a/pythonforandroid/patching.py

@@ -18,6 +18,7 @@ def is_platform(platform):
         return uname()[0] == platform
     return is_x
 
+
 is_linux = is_platform('Linux')
 is_darwin = is_platform('Darwin')
 
@@ -30,31 +31,31 @@ def is_arch(xarch):
 
 def is_api_gt(apiver):
     def is_x(recipe, **kwargs):
-        return recipe.ctx.android_min_api > apiver
+        return recipe.ctx.android_api > apiver
     return is_x
 
 
 def is_api_gte(apiver):
     def is_x(recipe, **kwargs):
-        return recipe.ctx.android_min_api >= apiver
+        return recipe.ctx.android_api >= apiver
     return is_x
 
 
 def is_api_lt(apiver):
     def is_x(recipe, **kwargs):
-        return recipe.ctx.android_min_api < apiver
+        return recipe.ctx.android_api < apiver
     return is_x
 
 
 def is_api_lte(apiver):
     def is_x(recipe, **kwargs):
-        return recipe.ctx.android_min_api <= apiver
+        return recipe.ctx.android_api <= apiver
     return is_x
 
 
 def is_api(apiver):
     def is_x(recipe, **kwargs):
-        return recipe.ctx.android_min_api == apiver
+        return recipe.ctx.android_api == apiver
     return is_x