added Travis CI configuration file
added Travis CI configuration file

* added Travis CI configuration

Build uses both clang and gcc compilers and compiles with the latest supported branches of Zabbix plus trunk.

* added step to configure Zabbix sources

Otherwise Zabbix headers needed to compile loadable module are incomplete.

* added bootstrap.sh invocation

This step is required since we're taking Zabbix sources from SVN.

* added step to leave Zabbix source directory

Otherwise subsequent invocation of the compiler cannot find the source file.

i-ky/zaipcs