Bug fixes, spacing and variable initialisation

[drpatelh]

Many thanks to contributing to nf-core/tools!

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PR checklist

• This comment contains a description of changes (with reason)
• If you've fixed a bug or added code that should be tested, add tests!
• Documentation in docs is updated
• CHANGELOG.md is updated
• README.md is updated

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• Fix Use checkIfExists #165 @ewels ?
• Consistent spacing adjustments between code-blocks in main.nf
• Consistent if( to if ( in template
• Correct new ASCII logo in email_template.txt
• Add file existence check to scrape_software_versions.py
• Initialise params.fasta and params.genome to suppress NF warning
• Add sensible resource labels to base.config and add example usage to fastqc process

[ewels]

Looking good! Few comments / minor suggested changes..

[drpatelh]

Just need to sort out whether I am implementing check_resource here too based on merging #408.

[ewels]

Nice work!