v0.3.0

Major changes

• Add documentation, images, installation and usage instructions to README.md. (#22, #17)
• Allow prior construction of a search query in Arx.search. (#18)
• Fix Arx.search query object yielding. (#20)

Minor changes

• Remove conditional with block_given? in Arx() method. (#16)
• Remove leading ampersand (&) from search query string. (#19)
• Add base paper categories and more aliases. (#21)