Scrape yourself
Open the url of the tweet, pass to HTML parser of your choice and extract the XPaths you are interested in.
Scraping is discussed in: http://docs.python-guide.org/en/latest/scenarios/scrape/
XPaths can be obtained by right-clicking to element you want, selecting "Inspect", right clicking on the highlighted line in Inspector and selecting "Copy" > "Copy XPath" if the structure of the site is always the same. Otherwise choose properties that define exactly the object you want.
In your case:
//div[contains(@class, 'permalink-tweet-container')]//strong[contains(@class, 'fullname')]/text()
will get you the name of the author and
//div[contains(@class, 'permalink-tweet-container')]//p[contains(@class, 'tweet-text')]//text()
will get you the content of the Tweet.
The full working example:
from lxml import html
import requests
page = requests.get('https://twitter.com/UniteAlbertans/status/899468829151043584')
tree = html.fromstring(page.content)
tree.xpath('//div[contains(@class, "permalink-tweet-container")]//p[contains(@class, "tweet-text")]//text()')
results in:
['Breaking:\n10 sailors missing, 5 injured after USS John S. McCain collides with merchant vessel near Singapore...\n\n', 'https://www.', 'washingtonpost.com/world/another-', 'us-navy-destroyer-collides-with-a-merchant-ship-rescue-efforts-underway/2017/08/20/c42f15b2-8602-11e7-9ce7-9e175d8953fa_story.html?utm_term=.e3e91fff99ba&wpisrc=al_alert-COMBO-world%252Bnation&wpmk=1', u'\xa0', u'\u2026', 'pic.twitter.com/UiGEZq7Eq6']