version bump
Merge branch 'release/0.157000'
v0.157000

    [ BUG FIXES ]
    * GH #799: Set current request earlier so log formats using requests
      will work. (Sawyer X)
    * GH #650: Provide default environment to app for templating.
      (Dávid Kovács, Chi Trinh)
    * GH #800: Better portability code, for different Windows situations.
      (Christian Walde)
    * Less littering of the test directories with session files. (Sawyer X)

    [ ENHANCEMENT ]
    * GH #810: strict && warnings in the app.pl. (Sawyer X)
    * Use to_app keyword in skeleton. (Sawyer X)
    * GH #801: Under production, server tokens are disabled. (Sawyer X)
    * GH #588, #779: Remove LWP::UserAgent in favor of HTTP::Tiny.
      (Dávid Kovács, simbabque, Sawyer X)
    * Remove all usages of Test::TCP in favor of Plack::Test. (Sawyer X)

    [ DOCUMENTATION ]
    * GH #802: Remove indication of warnings configuration option
      and add explanation in migration document. (Sawyer X)
    * GH #806: Link in main docs to the migration document. (Gabor Szabo)
    * GH #807: Update migration document with more session data,
      changes to app.pl, and Template::Toolkit configuration. (Gabor Szabo)
    * GH #813: Update migration document with information on encoding and
      usage of Plack::Request internally. (Gabor Szabo, Sawyer X)