Build with java7 by default.

android

All introduce a flag LEGACY_USE_JAVA6 to force java6 builds.
This is an unsupported configuration, and provided temporarily to iron out regressions and compare build output (if required.).

  • Increment the version check sequence number.
  • Move a more specific check (OpenJDK vs non OpenJDK) after the more general version check.
  • Update the link in the version check error message to the "initializing" page instead of the "download" page. The latter talks about repo, mainly.

masterは変わったけど、実際には4.5からになるのか、その次からになるのか。