added requirements
improved output of chosen language
differentiate if leo is called started directly or loaded as a module
Fix lookup for some words

For some words, like 'nutritive', the lookup failed because there's no
<side> tag with hc=0 attribute in leo.org's XML output, but rather two
with both <side> tags having hc attributes set to 1.

Fix this by not looking at the "hc" attribute, but using the <side>
tags and the words in them directly.

    $ ./leo nutritive
    translating to: ende
    nutritive   ernährend
    nutritive   Ernährungs...
    nutritive   Nähr...
    [...]
Merge branch 'fix/some-words-dont-work' of https://github.com/neingeist/leo-cli

fixes #3
remove debug message
install requests and beautifulsoup before
fix #2