Attempt to install oracle-xe-client on travis-ci

Testing Oracle setup for the first time. Temporarily disabled ctest run.
Use Bash shell to run travis-ci scripts

Fix echo call
Fix typo in Bash function tmstamp
Install Oracle GPG key for apt-get on travis-ci
Set ORACLE_HOME for InstantClient on travis-ci

Add newline at end of .sh files
Export ORACLE_HOME to global env on travis-ci. Fix broken apt-key.
Check ORACLE_HOME from script.sh builder
Still testing ORACLE_HOME export

Not sure why environment variable export is not working as expected.
Move common definitions to common.sh

Source common.sh into other travis-ci shell scripts.
Print ORACLE_HOME in FindOracle.cmake as STATUS
Re-enable ctest in travis-ci scripts.

First time Oracle tests should run against my public Oracle XE instance
available at: service=brzuchol.loskot.net user=soci_tester
password=soci_secret
Temporarily disable IN/OUT test (see #81)

This **temporary** comment-out allows to test Oracle setup on travis-ci.
Print timestamps in travis-ci build log