Update README.md

Author: kimkevin

README.md

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 # CachePot - Android Simple Data Cache
 
+[ ![Download](https://api.bintray.com/packages/kimkevin/maven/com.github.kimkevin%3Acachepot/images/download.svg) ](https://bintray.com/kimkevin/maven/com.github.kimkevin%3Acachepot/_latestVersion)
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 CachePot is a simple open source for data cache management and passing data object between Fragments without Pacelable and Serializable.
 
 > WARNING: It would be inappropriate to pass data both ways between different android applications, it's a better way to use `Intent` properly.