added ComplexSparseMatrixOperator to modular interface (log-det)
turned some debug messages into info messages
Merge pull request #1641 from karlnapf/develop

turned some debug messages into info messages
Merge pull request #1637 from lambday/feature/log_determinant

added ComplexSparseMatrixOperator to modular interface (log-det)
Disabled integration tests on travis
Random kitchen sinks