CalendarConversion.pm now uses YAML instead of YAML::XS.

Fixes #790. YAML is used instead of YAML::XS. Had to make changes to `calendar.yml` too.

This is my first PR for zeroclickinfo-goodies. I followed https://duck.co/duckduckhack/goodie_quickstart and used Codio to fix it. I can run the testcase for *CalendarConversion* successfully, but there are 3 other tests failing:

````
Test Summary Report                                                                                                                                                                                                              
-------------------                                                                                                                                                                                                              
t/ChineseZodiac.t         (Wstat: 512 Tests: 0 Failed: 0)                                                                                                                                                                        
  Non-zero exit status: 2                                                                                                                                                                                                        
  Parse errors: No plan found in TAP output                                                                                                                                                                                      
t/Conversions.t           (Wstat: 256 Tests: 115 Failed: 1)                                                                                                                                                                      
  Failed test:  80                                                                                                                                                                                                               
  Non-zero exit status: 1                                                                                                                                                                                                        
t/SunInfo.t               (Wstat: 512 Tests: 0 Failed: 0)                                                                                                                                                                        
  Non-zero exit status: 2                                                                                                                                                                                                        
  Parse errors: No plan found in TAP output                                                                                                                                                                                      
t/Uptime.t                (Wstat: 512 Tests: 0 Failed: 0)                                                                                                                                                                        
  Non-zero exit status: 2                                                                                                                                                                                                        
  Parse errors: No plan found in TAP output       
````

I don't think I broke them, because they are failing even after reverting my changes. If I did break something, please tell me so I can fix it again. :)