build shared library/python module, clean up CMake

libledger will now be built as a shared library. You can 'import ledger'
from python IFF you copy libledger.so to ledger.so or create a symlink.
no RENAME option on older CMake versions

The RENAME option for install(TARGETS ...) does not seem to be available
on all CMake versions.
Fix shared library and python module

Conflicts:
	src/CMakeLists.txt
python module file suffix is platform dependent
Create default scope from python session only if needed

Fixes test failures introduced with the commit
"Create default scope to read journal"
a9078767b8224a223f8942a1cb80d4544024387b
Update dependencies installation

for Mac Hombrew and Ubuntu Precise Pangolin
Add continuous integration using Travis CI
Correct log output for acprep check
initialize member variables of posts_to_org_table

This fixes test/baseline/cmd-org.test when built with clang.
update travis notification settings