Fix executable_path type error by utilising service when connecting to selenium

[malmike]

1. Fixed the executable_path TypeError https://github.com/clemfromspace/scrapy-selenium/issues/128
2. Fixing remote driver functionality by fixing the deprecated desired_capabilities for options.
3. Removed pip_tools when getting the installation requirements for the build in setup.py. Pip keeps updating its package structure and the current implementation breaks in versions pip >= 20 cause of the new package structure

[omars44]

@malmike Thank you

My hopes are very low for this to get merged, '2020'