Add EJS helpers for Specs pre-rendering + docs #123

Continuing with EJS pre-rendering set-up for specs, that allows to use includes in index.src and other custom logic, in one of the next releases we plane to add some helper functions like:

• includeMD(pathToFile) - for including AND processing markdown files in index.src
• includeFiles(glob) - for including a list of files one by one using glob
• includeExample(glob) - for including a list of files and wrapping them into source_exampe template