🐛 More better default values

- Mocks were enabled by default. Previoulsy, this was largely harmless as nothing happens unless mocks are referenced in a test file. To match the assumptions in more rigorous configuration handling and just to make a sensible default, this is disabled.
- Exception handling setting was previously handled entirely in code. This setting can be in the defaults and should be for clarity and readability.
- CMock’s plugin list was previously handled solely in code, including a default blank list. This hid the setting.

lib/ceedling/defaults.rb

@@ -303,7 +303,8 @@
 DEFAULT_CEEDLING_PROJECT_CONFIG = {
     :project => {
       # :build_root must be set by user
-      :use_mocks => true,
+      :use_mocks => false,
+      :use_exceptions => false,
       :compile_threads => 1,
       :test_threads => 1,
       :use_test_preprocessor => false,
@@ -385,7 +386,8 @@
 
     :cmock => {
       :includes => [],
-      :defines => []
+      :defines => [],
+      :plugins => []
     },
 
     :cexception => {