Create test/Project.toml to run tests

[pddshk]

Project.toml has no Pkg, Revise and Test packages, so running test StringCases produces such errors.

pkg> test StringCases
     Testing StringCases
      Status `/tmp/jl_YG3lQ7/Project.toml`
  [f22f4433] StringCases v0.1.0
      Status `/tmp/jl_YG3lQ7/Manifest.toml`
  [f22f4433] StringCases v0.1.0
     Testing Running tests...
ERROR: LoadError: ArgumentError: Package Pkg not found in current path:
- Run `import Pkg; Pkg.add("Pkg")` to install the Pkg package.

Stacktrace:
 [1] include(fname::String)
   @ Base.MainInclude ./client.jl:444
 [2] top-level scope
   @ none:6
in expression starting at /home/user/.julia/packages/StringCases/0gfCe/test/runtests.jl:1
ERROR: Package StringCases errored during testing

UPD. test script does not need to include Pkg and Revise

[pddshk]

Removed Manifest files and added them to .gitignore.

Added separate Project for tests, removed unused deps and reorganized them