Upgrade build to Gradle 2.13 [SPR-14215]

[spring-projects-issues]

Juergen Hoeller opened SPR-14215 and commented

Gradle 2.13 was released today... easily in time for our 4.3 RC2.

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Affects: 4.3 RC1

Issue Links:

• Upgrade build to Gradle 2.12 [SPR-14048] #18620 Upgrade build to Gradle 2.12
• Upgrade build to Gradle 2.14.1 [SPR-14362] #18934 Upgrade build to Gradle 2.14.1

Referenced from: commits bb1a031