GitLab

**Description**
Format int type and unify np.nan in diagnosis output files.

**Major Revision**
- format all int columns 
- unify na values to 'N/A' in json,jsonl,md,html files

**Description**
 Make baseline check optional in data diagnosis and fix bugs.

**Major Revision**
- make baseline file optional in data diagnosis
- fix bugs of output in md and excel format when 'function' is not in the rule
- fix bug in multi_rules function that miss/failed test may failed the whole process

**Minor Revision**
- revise doc related with data diagnosis
- resolve warning message about baseline not found check, only raise exception if baseline not found in the  'variance' function
- move summary fields into top of json file
- unify 'Index','machine' -> 'index' in output file

**Description**
Add failure check feature in data diagnosis.

**Major Revision**
- Add failure check rule op to support that if there exists metric_regex not been matched by any metric in result, label as failedtest
- Split performance issue and failedtest in categories


**Minor Revision**
- replace DataFrame.append() with pd.concat since append() will be removed in later version of pandas

**Description**
Add md and html output format for DataDiagnosis.

**Major Revision**
- add md and html support in file_handler
- add interface in DataDiagnosis for md and HTML output

**Minor Revision**
- move excel and json output interface into DataDiagnosis