Add "Line Based" support

+ Add keymaps for "Line Based" runs
+ Add menus for "Line Based" runs
+ Update grammars.coffee for "Line Based" runs
Create a CodeContext object to wrap some logic
Use CodeContext#filepath not CodeContext#getPath
Create spec/code-context-spec.coffee
Delete boiler plate spec file
Always send codeContext as an argument to buildArgs
Update header-view title for line based runs
Fix fileColonLine behavior

+ Update related specs
Add a new spec for testing getCode()
Reorganize code layout

* Move CodeContext creation into its own build step
* Move language validation to its own function
* Finish extracting lang, codeContext
* Simplify line based path
* Separate line and file/selection runs
* Simplify code context selection
Merge pull request #1 from rgbkrk/move_code_context_creation

Move code context creation
Add lineNumber to Selection Based runs
Update demo gif in README.md
Merge pull request #112 from erran/line-based-execution

Add "Line Based" support :shipit: