Added isBinarySearch tree question.
Merge branch 'master' of https://github.com/Eric-Gonzalez/JavaQuestions

Conflicts:
	src/ModifiedStack.java
	src/ModifiedStackTest.java
	src/SpreadSheetColumns.java
	src/SpreadSheetColumnsTest.java
	src/com/cci/ModifiedStack.java
	src/com/cci/ModifiedStackTest.java
	src/com/cci/SpreadSheetColumns.java
	src/com/cci/SpreadSheetColumnsTest.java
	src/main/java/ModifiedStack.java
	src/main/java/SpreadSheetColumns.java
	src/test/java/ModifiedStackTest.java
	src/test/java/SpreadSheetColumnsTest.java
Gradle updates.