update minimum sdk version to 21

Author: sjlombardo

Diff for: README.md

@@ -5,7 +5,7 @@ The latest AAR binary package information can be [here](https://www.zetetic.net/
 
 ### Compatibility
 
-SQLCipher for Android runs on Android from 4.1 (Jelly Bean), for `armeabi-v7a`, `x86`, `x86_64`, and `arm64_v8a` architectures.
+SQLCipher for Android runs on Android from 5.0 (API 21), for `armeabi-v7a`, `x86`, `x86_64`, and `arm64_v8a` architectures.
 
 ### Contributions
 

Diff for: build.gradle

@@ -58,7 +58,7 @@ ext {
   mavenDeveloperEmail = "[email protected]"
   mavenDeveloperOrganization = "Zetetic LLC"
   mavenDeveloperUrl = "https://www.zetetic.net"
-  minimumAndroidSdkVersion = 16
+  minimumAndroidSdkVersion = 21
   minimumAndroid64BitSdkVersion = 21
   targetAndroidSdkVersion = 26
   compileAndroidSdkVersion = 26