compile source code error by make build_linux

[yixy]

Issue Description

Type: bug report

Describe what happened (or what feature you want)

There are some errors when using make build_linux to compile the source code:

1. cannot compile chaosblade-operator in docker.
2. mvn command not found in docker, because of M2_HOME and PATH variable not setting in Dockfile.

Describe what you expected to happen

make build_linux compiles correctly

Tell us your environment

root@instance-1:/myworkspace/src/github.com/chaosblade-io/chaosblade# uname -a
Linux instance-1 4.15.0-1052-gcp #56-Ubuntu SMP Thu Dec 19 10:54:56 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux

[xcaspar]

@yixy I have fixed it, please pull the master branch and compile.

[yixy]

@xcaspar It works, THX :)