Days 21, 22 and 23 of 2013-04 challenge

Add entries for new idioms:
    itchy feet
    true as steel
    coming out of ears
Remove "someone or something" from idiom of day 2

By convention, the indefinite pronouns in an idiom are not included in
the heading of each day's entry. Therefore, remove the indefine pronouns
from idiom of day 2. The entry of day 2 appears as

    "drop someone or something like a hot potato"

which needs to be modified to

    "drop like a hot potato"