Add SeisKit.jl to the list of seismic tools

[juliohm]

Project name:

SeisKit.jl

Project website/repository:

https://github.com/JuliaEarth/SeisKit.jl

License:

MIT

Submission type:

New Software Project

Checklist for all pull requests:

• Project is certified awesome

• The project is open-source and accessible.
• Searched the existing entries to make sure this is not a duplicate.
• Contains only a single addition (make separate PRs if adding more than one).
• Added the link to the bottom of the relevant category.
• Created a new category only if necessary.

• Add icon from the media/icon/ folder if applicable (e.g., ![Python](media/icon/python.png) ).
• Checked spelling and grammar.
• Removed trailing whitespace and periods.
• Confirm the dash – is not a minus -.
• Used title-casing (AP style) for project name.

Checklist for new software projects:

• Link the code repository rather than the website/documentation
• Installation instructions present
• Documentation looks great
• Examples or Tutorials to follow
• Tests and Travis CI running

[juliohm]

Appreciate it if someone could review this.