Changes for 0.4.0

[HyukjinKwon]

This PR prepares the release for 0.4.0.

This will include the changes below:

• Support for PERMISSIVE/DROPMALFORMED mode and corrupt record option. Support for PERMISSIVE/DROPMALFORMED mode and corrupt record option. #107
• Change default values for valueTag and attributePrefix to avoid always require field escape for some apis Change default values for valueTag and attributePrefix to avoid always require field escape for some apis. #142
• deprecates saveAsXmlFile and promote the usage of write(). Upgrade spark 2.0 and prepare 0.4.0-SNAPSHOT #150
• deprecates xmlFile and promote the usage of read(). Upgrade spark 2.0 and prepare 0.4.0-SNAPSHOT #150
• drops 1.x compatibility from 0.4.0. Upgrade spark 2.0 and prepare 0.4.0-SNAPSHOT #150
• makes not supporting UserDefinedType as it became private. Upgrade spark 2.0 and prepare 0.4.0-SNAPSHOT #150

[codecov-io]

Current coverage is 87.85% (diff: 100%)

Merging #176 into master will not change coverage

@@             master       #176   diff @@
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  Files            15         15          
  Lines           708        708          
  Methods         641        641          
  Messages          0          0          
  Branches         67         67          
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  Hits            622        622          
  Misses           86         86          
  Partials          0          0          

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[HyukjinKwon]

I am going to merge this.