Some minor optimize

[vongosling]

1. Add .gitignore file to ignore some unexpected commit file list
2. Remove getOutputDirectory method ,so as to utilize last local variant outputDirectory
3. Remove some warnings in eclipse(remove useless warning suppress)
4. Modify default thrift'idl root directory to be compliant with maven default directory guide

[vongosling]

This maven plugin is good job,How can i become a code contributor

[vongosling]

oh.I think of I modified Thrift class default visibility to public ,because someone may invoke it in the project code directly~

[vongosling]

@dtrott Can you check this request

[dtrott]

No value add.