Bug 846845 - [MMS][SMS][Tests] add tests and simplify Utils

```bash
  [SMS] Utils
    ✓ [SMS] Utils.escapeHTML (valid) 
    ✓ [SMS] Utils.escapeHTML (invalid) 
    ✓ [SMS] Utils.getFormattedHour([String|Number|Date]) 
    ✓ [SMS] Utils.getDayDate(UTSMS) 
    ✓ [SMS] Utils.getHeaderDate(today [String|Number|Date]) 
    ✓ [SMS] Utils.getHeaderDate(yesterday [String|Number|Date]) 
    ✓ [SMS] Utils.getPhoneDetails(number, contact, callback) 
    ✓ [SMS] Utils.getPhoneDetails(number, null, callback) 
    ✓ [SMS] Utils.getPhoneDetails(number (wrong number), contact, callback) 
    ✓ [SMS] Utils.getPhoneDetails(number, contact (blank name), callback) 
```

All, with the exception of escapeHTML, will pass before and after code simplification commit. The escapeHTML implementation was purely incomplete and requires the middle commit that corrected the entities and completed the conversion of `<` and `>`