Improve text readability of session descriptions

[johnjohndoe]

The textual description of a session is currently shown as can be seen in the following example screenshot taken from a Nexus 9 tablet, running version 0.5.3 of the app. The text size is rather small and the line height is "normal".

Proposal

To improve the readability of the text I suggest to:

1. Increase the text size on devices with a larger screen size such as tablets/phablets
2. Increase the line height for the description paragraph. I made positive experience with a value such as 135% or 150% of the text size when layouting text paragraphs in other applications.