Remove .gradle directory + add the package name for CTest compatibility

.gitignore

.gradle/4.7/fileChanges/last-build.bin

.gradle/4.7/fileHashes/fileHashes.bin

.gradle/4.7/fileHashes/fileHashes.lock

.gradle/4.7/taskHistory/taskHistory.bin

.gradle/4.7/taskHistory/taskHistory.lock

.gradle/buildOutputCleanup/buildOutputCleanup.lock

.gradle/buildOutputCleanup/cache.properties

.gradle/buildOutputCleanup/outputFiles.bin

.gradle/vcsWorkingDirs/gc.properties

build.gradle

src/main/CMakeLists.txt

src/main/java/Complex.java

src/main/java/Main.java

src/test/java/ComplexTest.java