For the consumer it should not matter if fmt has been added to the
project as subdirectory or via find_package. With the alias targets
the library can be always imported via fmt::fmt.

* Gradle

Gradle support to make ease of import in Android Java projects.

* Gradle

Gradle support for Android projects.
For command line build, `gradle assembe` will trigger build phase

 - Config for Android .so file generation
 - Commented build.gradle
 - Automatic file copy after build
 - Dummy AndroidManifest file

* Build with Gradle

 - Build job for Travis CI
 - Moved gradle file to support/

* Gradle Path

 - Absolute path for Gradle binary

* File check after Gradle build

 - Additional script for build success
 - Check the Gradle's `assemble.doLast` task

GCC 7.3 complains that this is not a compile time constant.

test/format-test.cc: In member function ‘virtual void FormatTest_FormatStringErrors_Test::TestBody()’:
test/format-test.cc:1919:3: error: non-constant condition for static assertion
   static_assert(test_error<__VA_ARGS__>(fmt, error), "")
   ^
test/format-test.cc:1924:3: note: in expansion of macro ‘EXPECT_ERROR’
   EXPECT_ERROR("{0:s", "unknown format specifier", Date);
   ^~~~~~~~~~~~

GCC 7.3 complains about uninitialized varaibles in constexpr context.

C++11 does not support deduction of return type.