Merge pull request #41 from xbe/travis-ci

Add Travis CI builds and tests

.travis.yml

+sudo: required
+
+language:
+  - cpp
+
+services:
+  - docker
+
+script:
+  - ./build-docker-image.sh
+  - ./build-debug.sh
+  - build-debug/tests/bpftrace_test

README.md

+[![Build Status](https://travis-ci.org/ajor/bpftrace.svg?branch=master)](https://travis-ci.org/ajor/bpftrace)
+
 # BPFtrace
 
 BPFtrace is a [DTrace](http://dtrace.org)-style dynamic tracing tool for linux, based on the extended BPF capabilities available in recent Linux kernels. BPFtrace uses [LLVM](http://llvm.org) as a backend to compile scripts to BPF-bytecode and makes use of [BCC](https://github.com/iovisor/bcc) for interacting with the Linux BPF system.