Ignore namespaces while reading.

[HyukjinKwon]

#74

This is a workaround to read a XML files with namespaces.
Currently, this ignores namespaces but we might need to handle this by options or other ways.

This PR makes this library able to read a XML file rather than ignoring the rows as malformed rows below:

11:25:32.517 WARN com.databricks.spark.xml.util.InferSchema$: Dropping malformed row: <Topic r:id="">        <catid>1</catid>    </Topic>
root

[codecov-io]

Current coverage is 89.42%

Merging #75 into master will increase coverage by +0.20% as of 4041114

@@            master     #75   diff @@
======================================
  Files           12      12       
  Stmts          622     624     +2
  Branches        86      86       
  Methods          0       0       
======================================
+ Hit            555     558     +3
  Partial          0       0       
+ Missed          67      66     -1

Review entire Coverage Diff as of 4041114

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[HyukjinKwon]

I am going to merge this.

[HyukjinKwon]

Merged.