run autoreconf to generate configure script
travis needs some more autoconf macros
Remove AC_CHECK_HEADER_STDBOOL for travis
libconfig++ > 1.3 should be enough
ParseException in libconfig++ < 1.4 does not have a getFile method
getLine() and getError() are not const in libconfig++ < 1.4
more portable library detection

 * use pkg-config for libconfig++ and crypto++
 * use -lboost_thread-mt instead of -lboost_thread
movin filters into a separate header
pam support
restructuring includes and namespaces
splitting tests according to their dependencies
making dependencies optional

 * only add PamUserDB when pam is available
 * only add File*DB when libconfig is available
 * only add Sha256Filter when crypto++ is available
commenting out AC_CHECK_HEADER_STDBOOL
build gmock and gtest only when running tests
Merge branch 'master' into develop

Conflicts:
	.gitignore
updating installation instructions
adding travis build status to README.md
Merge pull request #2 from rmohr/develop

After massive refactoring, stable again