Zero determinant tests added.
Determinant by LU decomposition fixed (issue #91)
Merge remote-tracking branch 'upstream/master'

Conflicts:
	src/main/java/org/la4j/matrix/AbstractMatrix.java
Create AbstractMatrix.java
Update AbstractMatrixTest.java
Added some rank tests
Fixed exception (issue #106)
Added some tests for matrix inverting and fixed type of exception in zero determinant matrices invertion (issues #102 #106)
Fixed test
Merge pull request #90 from SamoylovMD/master

New tests for rank/inverse by Maxim