Implement gyroignore

[deepanjan90]

fixes #156

Gyro Ignore rule

• A file named .gyroignore at the .gyro dir in the root of the project is read to decide what should be processed by gyro.
• If a config file is ignored, its corresponding state file [If exists] is also ignored.
• All paths are relative to the root of the project.
• A blank line matches no files.
• The pound # serves as a comment.
• Trailing spaces are ignored.
• The exclamation! negates the pattern. Any matching file excluded by a pattern will become included again only if this pattern comes before the excluding patterns.
• The slash / is used as the directory separator.
• * matches anything except a slash /. Ex. abc/* will match all files directly present under the abc directory. But will not match files in sub directories. abc/d* will match all files under abc that starts with d.
• ** will match everything. Ex abc/** will match all files under abc directly under it or part of subdirectories . **/abc will match any file named abc anywhere. abc/**/def will match all files that lie between the directory abc and def anywhere. abc** will be treated as abc* and follow the rules of *.